Week 5 Flashcards
1
Q
Lipoproteins
- Definition
- Where do lipids come from? Where do they originate?
- function
- synthesized
A
- large macromolecule complexes of protein and lipids that help in transport of lipids
- Can be dietary or synthesized
- can carry dietary lipids from intestine via blood to different target organs for different functions (use or storage)
- Synthesized (endogenous): made in liver, converts excess carbohydrates carbons to fatty acid (FA) and cholesterol will change the FA to triglycerides and transpose them to the lipoprotein so that they can be taken to different tissues for utilization and storage
2
Q
different kinds of lipoproteins?
A
- chylomicron
- VLDL
- LDL
- HDL
3
Q
Chylomicron
- size/density…why?
- What do they do?
- Identifying apoproteins
- Where are they from?
- maturation
- trading with HDL
- what do they turn into?
A
- lowest density and highest particle size; have higher tri-glyceride content and low protien contest
- Carry dietary lipids absorbed in intestine to different parts of the body abundant in them to different tissues (muscles and adipose, etc.) for usage/storage.
- ApoB48, C2, E
- intestines the chylomicron will first be released into lymphatics and get put into systemic circulation as they mature
- While traveling they gain other apo-lipo proteins ( C2 and E from HDL) in the blood making them mature chylomicrons
- After they have distributed tri-acyl glycerols they become remnant chylomicrons which then goes back to the liver and uses apoE for cytoplasmic uptake into hepatocyte and whatever cholesterol it has left will be reused or dumped in bile.
4
Q
VLDL
- size/density
- apoproteins
- what does it carry?
- where is it produced? carries?
- fate?
- IDL
A
- slightly more dense than chylomicron and is slightly smaller in particle size than chylomicron
- ApoE, ApoB100, and Apo C2
- cholesterol and triglycerides but different from chylomicrons because they are endogenous meaning that the liver makes them–also carries cholesterol esters
- in the liver and carries endogenous fats like tri-glyceride, cholesterol, and cholesterol esters that are synthesized from carbohydrate carbons
- Once they drop off some of the cholesterol and majority of tri-glyceride to the tissue for usage and storage it becomes more dense making it IDL (15% protein, 85% lipid)
- Distributes the remnant triglycerides to other tissues making it an LDL
5
Q
LDL
- what does it have?
- What are cholesterol esters?
- made from?
- apoproteins
- how does it function
A
- High in cholesterol and cholesterol esters, low in triglycerides
- Cholesterol esterified to FA molecules; it is preferred transport form of cholesterol
- IDL which is made from VLDL
- gives up APOC2 and APO E–which are recylced; remains with ApoB100 ONLY
- usually does not go back to liver and is mostly absorbed by receptor mediated mechanisms in different cells who need cholesterol. Since it does not usually go back to liver and it can be taken up by other cells using LDLR
6
Q
HDL
- density and size
- What do they do? Why is it good?
- name of process
A
□ Highest density because it has high amount of protein and smaller size
- It distributes lots of apo-proteins and helps with maturation of other lipoprotein, but also takes excess cholesterol (from peripheral cells, foam cells for example) and triglycerides (from chylomicron) back to liver for usage/elimination
- reverse transport of cholesterol
7
Q
What happens with high fat diet?
A
- chylomicron levels will rise because the fat you’re getting is coming from diet; eventually some cholesterol and triacylglycerols will come back via the chylomicron remnants and may be packaged into VLDL, so VLDL and and LDL might rise later on
8
Q
similarity between Apo B 48 and 100
A
- ApoB 48 is made in enterocytes, is truncated version of the entire peptide (only 48% of normal peptide), because when it gets transcribed it goes through RNA editing so a stop codon is introduced abruptly, making shorter version of protein
- ApoB 100 is made from same gene and made in hepatocyte; will be full version of the gene (w/o any RNA editing)
9
Q
If a cell can make cholesterol when would it want to get cholesterol from LDL?
A
- When there is low intra-cellular levels of cholesterol– for example, if you are on a statin which inhibits biosynthesis of cholesterol then the cell will begin to have intercellular crisis for cholesterol and that acts as stimulus for increased production of LDLR which will go to the surface and bind LDL
10
Q
What does LDLR recognize on LDL in order to have it bind?
A
It will recognize the ApoB100, which also helps the LDL fit into the LDLR
11
Q
familial hypercholesterolemia
- locus heterogeneity
- cause and explanation
A
- so two mutations on very different genes having similar effects.
- defective receptor: receptor is unable to make it into membrane or is ineffective at binding LDL so LDL will accumulate in blood because it cannot be taken into the cell leading to a high cholesterol level
- Other mutation is on the ApoB100 portion on the LDL, so even though the receptor works just fine LDL is unable to bind because it cannot be recognized/ is having a hard time fitting into the receptor– this means that LDL cannot be taken in, which causes build up of LDL which leads to hypercholesterolemia
12
Q
Link high levels of LDL to CV diseases
A
- high amount of LDL in the blood there is high chances of LDL being trapped to vessel wall and when they get trapped they are exposed to reactive oxygen which will then modify apoB proteins on the surface and the lipids so this oxidized LDL looks very foreign (does not look endogenous) which will induce immune reaction which will cause monocytes to be attracted to the area, they will differentiate into macrophages. The macrophages will then bind to the foreign looking oxidized LDL and when it phagocytoses it the macrophage is turned into a lipid loaded foam cell. When foam cells accumulate they will become calcified which will induce inflammation which can damage surrounding cells in the vessel and the accumulation of calcified foam cells are the entero-sclerotic plaques which will reduce the circumference of the artery/blood vessel which makes patient prone to cardiovascular disease such as an MI (myocardial infarction)
13
Q
Reverse transport of cholesterol
- LCAT
A
- HDL will distribute its apoproteins and collect cholesterol from peripheral cells (such as foam cells or VLDL) and then comes back to liver and dumps the cholesterol and forms cholesterol ester for usage or elimination
- Lecithin–cholesterol acyltransferase: helps esterify the cholesterol picked up by the HDL by binding it to a fatty acid and then packing it to the center; Once this happens the HDL is considered mature
14
Q
Fat Storage
- when?
- high hormone
- effect of insulin
- coenzyme
- what happens?
A
- Fed state
- Insulin will have role to play in the storage of the fat in order to bring everything back to homeostasis
- activates lipoprotein lipase through dephosphorylation which is in the membrane of different cells (adipose tissue or muscle cells) and this facilitates storage of dietary fats
- apoc2 will further activate lipoprotein lipase and it will begin to break TG into glycerol and Fatty acids.
- Glycerol goes into liver and goes into glycolysis while fatty acids gets into the peripheral cell where it would be stored or used
15
Q
Fat mobilization
- when?
- hormone?
- how do they work?
A
- Fasted state
- Glucagon; Epinephrine and cortisol may also be high during this time
- Glucagon and epinephrine will bind to g protein coupled receptors which increases adenyl cyclase which causes increase in cAMP (secondary messenger) will phosphorylate and activate PKA, PKA will phosphorylate and activate hormone sensitive lipase (the most important hormone present in the adipocytes for lipolysis), hormone sensitive lipase will then break down the tri-glyceride into fatty acids and glycerol and then release them out into the blood to be dispersed to tissues
16
Q
Palmitic acid
- what is it?
- Why is it special?
- where does it get its carbons?
A
- 16 carbon fatty acid chain
- Primary fatty acid that is made in liver– liver will first synthesize Palmitic acid and if it needs a different kind of acid (steric acid or malic acid) it will modify palmitic acid
- producing 14 carbons from malonyl CoA and adding one acetyl coA making it a 16 carbon chain; Each reaction with malonyl CoA adds 2 carbons–so 7*2=14
17
Q
How can we link Palmitic acid, cholesterol, and acetyl CoA
A
- Need acetyl CoA to make cholesterol and fatty acid
- When FA breaks down it breaks into acetyl CoA
18
Q
Where does Acetyl CoA come from suring fatty acid synthesis?
A
- From glucose carbons or from ketogenic AA (lysine and leucine)
- Their carbon structure will break down directly into acetyl CoA
19
Q
Fatty Acid synthesis first step
- rate limiting enzyme
- co-enzyme
- regulation in fed state vs fasting state
- allosteric activator
- citrate shuttle
- negative allosteric
A
- Acetyl CoA carboxylase carboxylates acetyl CoA to malonyl CoA by adding a carboxyl group
- All carboxylation are done by by Vit B
- In fed state it is activated by insulin through dephosphorylation (in adipose and liver)
- In fasting state it will be inactivated by glucagon phosphorylating it
- Allo act.: High amount of citrate in the cell it will upregulate Acetyl CoA carboxylase because high citrate means there is a lot of energy in the cell because you have high amount of glucose carbons causing high amount of acetyl CoA which forms a lot of citrate and if that stays there it will inhibit citrate synthase which will stop TCA
- Citrate shuttle: Since acetyl CoA cannot get out of mitochondria it is converted in TCA to citrate gets out of mito through transporter goes back into oxaloacetate and acetyl CoA and then that acetyl CoA will be turned into Malonyl CoA
- High amount of palmitic acid in liver already will down regulate Acetyl CoA carboxylase
20
Q
Fatty acid synthesis
- where does it happen?
- type of reaction
- what does it require? and what do each of those require?
- enzymes
- number of cycles– palmitic acid
A
- Made by liver and adipose tissue
- multi-reaction step: involves condensation, reduction, dehydration, reduction
- requires several reaction cycles, Each cycle has 4 different types of reactions in it
- Condensation enzyme is a synthase, Reduction enzymes is a reductase, Dehydration enzyme is a dehydrotase, And then one more reductase
- depends on the chain length of the fatty acid; Palmitic acid is 7 cycles
21
Q
Enzyme complex responsible for all the enzymes needed to produce fatty acid?
- number of domains
- what helps it?
A
○ FAS: fatty acid synthase complex
- has 7 domains and each has an active site with its own separate enzyme
- Also uses acyl carrier proteins help to shuttle intermediates from one domain to the next
22
Q
First reaction cycle of FA synthesis
- what happens?
- and then?
A
- Condenses acetyl Coa (2 carbons) and a malonyl CoA (2 carbons) making 4 carbon intermediate
- Thereafter, every cycle adds one malonyl CoA to intermediate making it grow by 2 carbons until it achieves 16 carbon chain
23
Q
Commonality between cholesterol and fatty acid synthesis?
A
- Coming from acteyl CoA
- Predominately made in the liver and steroid hormone synthesizing cells– but all nucleated cells can make it
24
Q
Process of cholesterol synthesis
- what comes together? what enzyme is used?
- what are the intermediates and what do they lead to?
A
- Acetyl CoA and Acetoacetyl CoA (ketone) condense together to form HMG-CoA (Hydroxy methyl gluteral co enzyme A) the next step leads to formation of mevalonate by HMG-CoA reductase which is the rate limiting enzyme
- From mevalonate we make a lot of pyrophosphate intermediates which helps to make a lot of other things that the cells uses (so there are important). From the pyrophosphate intermediate we get a squalene which goes to lanosterol and then cholesterol
25
Pyrophophates
- name some
- what are they?
- where are they used?
- what can they make? what happens with statin?
- what cells suffer the most?
- Isopentenyl pyrophosphate importance
- isopentenyl/geranyl/farnesyl)
- They are cell signaling molecules
- Used in osteoclasts to form ruffle border and in ETC
- help in making co-enzyme Q so if cholesterol biosynthesis is inhibited by statin you will have decrease in Co Q-- which will affect ETC and ATP production
- Cells that suffer the most are muscles--this is what causes muscle cramping/pain with statins
- help to activate intracellular cell signaling- like RO RAS by activating hydrophobic group to cell molecules
26
Regulation of HMG CoA reductase
- what is it?
- hormonal regulation; fed vs fasting
- intracellular regulation; high vs low cholesterol
- HMG CoA reductase is the rate-limiting enzyme.
- Hormonal Regulation: In the fed state, insulin will activate phosphatases which will dephosphorylate HMG CoA and turn it on, causing an upregulation of cholesterol biosynthesis; In the fasted state (high levels of glucagon), there will be high amounts of intracellular AMP. High amounts of AMP will activate AMP-dependent protein kinase--> phosphorylate HMG CoA---> turn off/inactivate HMG CoA reductase --> downregulation of cholesterol biosynthesis
- High amounts of intracellular cholesterol/sterols--> turns on expression of proteases--> proteolytically cleave HMG CoA---> reduce levels of HMG CoA in the cells, downregulate cholesterol synthesis;
- Cholesterol deficient--> upregulate LDL receptors to allow for more cholesterol in the cell AND to up upregulate cholesterol biosynthesis, cholesterol dissociates from SCAP within the ER membrane--> cholesterol can't keep SCAP and SREBP in the ER membrane anymore--> will move from the ER to the Golgi membrane--> the N-terminal end will get cleaved off and released into the cytoplasm--> N-terminal end is a transcription factor--> goes into the nucleus and bind the steroid response element (the promotor of HMG CoA reductase)--> upregulates HMG CoA reductase production--> upregulates cholesterol biosynthesis within the cell
27
Oxidation of Fats
- occurs
- how does size effect?
- in the mitochondria
- Short (<6 C) and medium (6-12) fatty acids enter the mitochondria right away but long-chain fatty acids (13-24 carbons) are shuttled in through the Carnitine shuttle. Very long-chain fatty acids (>24 carbons) have to go to a peroxisome first to undergo partial oxidation to become a long-chain
28
location of catbolic vs anabolic processes
| - why?
○ The majority of anabolic processes occur in the cytoplasm and the majority of catabolic processes occur in the mitochondria.
- Because catabolic processes produce energy and the mitochondria is the powerhouse of the cell…
29
Oxidation of Fats Pathway
- start at the carboxyl terminal end rather than the methyl terminal end
- Coenzyme A is added to the Fatty Acid by AcylCoA synthetase (requires 2 ATP for each fatty acid to be activated) forming Fatty-Acyl Coenzyme A (FACoA); this enters the mitochondria
- Once it is in the intermembrane space,FACoA swaps its' CoA for carnitine by the enzyme CPT1 (carnitine palmitoyltransferase I).
which is then transported into the matrix by Carnitine-Acylcarnitine translocase ( will bring FA-carnitine in and take pre-carnitine out of the matrix.)
- CPTII (carnitine palmitoyltransferase II) in the inner mitochondrial membrane swaps the carnitine out for CoA activating the fatty acid and it enters Beta oxidation
30
Carnetine
- (made endogenously in the kidney or obtained exogenously through diet of animal-based foods)
- The body would prefer to obtain carnitine from the diet rather than having to make it itself because it requires a lot of energy and makes very little product (Carnitine) compared to the amount of substrate required.
31
- Will newly synthesized FAs be simultaneously oxidized
| - regulatory mechanism
- No because if the cell is synthesizing and degrading at the same time, it will use up all of its' ATP and end up dying
- Conversion of Acetyl CoA to Malonyl CoA in the cytoplasm by Acetyl CoA carboxylase--> increases concentration of Malonyl CoA--> inhibits CPT1--> Carnitine can't be attached--> FA can't enter the mitochondria--> can't undergo oxidation while synthesis is occuring
32
CPT1 deficiency
- what is happening
- effects? kidney, liver
- ketones
- neuro sxs
- Is not swapping CoA for carnitine, allowing for buildup of free carnitine in the blood.
- kidneys try to get rid of some of it, resulting in carnitine in the urine and High acylted FAs
- Glycogenolysis is likely happening but the liver will run out of glycogen at some point. We should have back up from gluconeogenesis but there are low amounts of fatty acids being burned resulting in low amounts of acetyl CoA and ketones and since Acetyl CoA is an activator of pyruvate carboxylase which is the first enzyme of gluconeogenesis (Pyruvate to Oxaloacetate) gluconeogenesis can't start and glucose levels start dropping
- Because fat is not burning , there will be low amounts of Acetyl CoA which usually forms ketones
- neurologic symptoms down the line because the brain can only use glucose and ketones as an energy source and both of these will eventually be low!
33
CPT2 deficiency
- what is it?
- kidney?
- present as high levels of carnitine in the mitochondria that may eventually come out into the blood but would be acylated carnitine (not free carnitine).
- kidney unable to filter out acylated carnitine because it is too big so its not in the urine.
34
primary carnitine deficiency
transport that reabsorbs carnitine in the kidneys are defective so the patient can't keep carnitine in the blood and loses all the carnitine in the urine
35
cycles of oxidation
- how does it occur? what does it release? ex?
- do the math for palmitic acid
- products of cycle
- types of reactions
- where do products go?
- each cycle will release 2 carbons in the form of acetyl CoA. (So when you burn a palmitic acid (16 carbon fatty acid), you will get 8 acetyl CoA)
- 7 cycles of oxidation each release 1 acetyl CoA (2 carbons each)--> (7x1=7 )--> 7 acetyl CoA (14 carbons total); And the last 2 carbons at the methyl terminal end will be left as the final acetyl CoA. (totaling 8 acetyl CoA, accounting for each of the 16 carbons)
- produce 1 NADH and 1 FADH2
- Starts with dehydrogenation with the enzyme Acyl CoA dehydrogenase (known as CADs), then hydrogenation step, Third is another dehydrogenation step, and finally in the last reaction, coenzyme A will come in which will lead to produciton of Acetyl CoA which will come out as a product of each cycle along with an NADH and FADH2
- Acetyl CoA will go into the TCA cycle to make more NADH and FADH2 and the NADH and FADH2 produced here will go directly into the ETC cycle to make ATP
36
Acyl CoA dehydrogenase
| - types
- SCAD= Acyl CoA Dehydrogenase for short-chain fatty acids
- MCAD= for medium-chain fatty acid
- LCAD= for long-chain fatty acid
- VLCAD= for very long-chain fatty acid
37
Deficiency of MCAD
common genetic disorder which will lead to decreased oxidation of medium-chain fatty acids in the liver--> accumulation of FAs in the liver--> increase triglyceride produciton--> increase VLDL--> fat accumulation in hepatocytes--> fatty liver
38
Types of fats
| - from the ocean?
- Saturated, Unsaturated, Transfats
| - DHA
39
Saturated Fats
- Chemical structure
- Physical state
- Physiologic state
- Endogenous
- major effects on health--length
- No double bonds, fully saturated with hydrogen, Will be stiff, flat chain that can stack up on one another
- solid at room temperature
- More susceptible to oxidation to make energy
- Made in the body endogenously as palmitic acid
- increase cardiovascular risk(not fully elucidated), can raise LDL cholesterol
- when looking at the health effects of saturated fats, it really depends on what length of saturated fat because medium-chain fatty acids can aid in weight loss and improve cardiovascular function.
40
Chain Length
- source of short
- source of medium-- best place to get them--how can they help?
- source of long chain in diet-- effect on metabolism
- source of very-long-chains
- microbiota including acetate, propionate, and butyrate also some in dairy
- Coconut oil and dairy products (goat milk)-- Coconut oil is the place to go for highest content of medium chain triglycerides (over 50%)-- may be helpful for weight loss and other metabolic effects
- Saturated: Meat, dairy, and palm oil; Unsaturated: Olive oil, soybean, Flax oil; long chains depend upon the carnitine shuttle which expends a lot of energy (2ATP)
- C26 (cerotic acid) --there are some genetic conditions where the body can't break it down
41
Vegetable oil and fats
- All of the vegetable oils can give us a combination of different fatty acids in different amounts
- olive oil: oleic (omega 9)
- soybea: linoleic (omega 6)
- flax oil: α-linolenic (omega 3)
42
Monounsaturated Fats
- Chemical Structure?
- Physical State?
- Physiologic Functions
- Effects on Health?
- sources
- One double bond located at the 9th position (omega-9s)
- Liquid but can get a little cloudy/thick if you put them in the fridge
- can be incorporated in the membrane and can be used for energy
- can reduce LDL
- olive oil, nuts, as well as avocados
43
Polyunsaturated Fats
- Chemical Structure
- omega 3 vs 6 structure
- Physical State
- Physiologic Functions
- Effects on health
- Multiple double bonds (at least 2)
- location of the first double bond in relation to the omega end determines whether it is omega-3 or omega-6
- Liquid at room temperature
- These help contribute to membrane flexibility and are also precursors for eicosanoids (inflammatory products such as prostaglandins)
- lower risk of cardio vascular disease and death in general
44
Essential Fats:
- which ones?
- why?
- common food sources for 6?
- sources of 3
- ratio of inflammation
- omega 6 and omega 3
- because we don't make them in the body and must get them in the diet.
- Sunflower oil (vegetable oil), chicken (in small amounts)
- found in Flax seeds, chia seeds, hemp seeds, walnuts (probably the highest source for nuts)
- 16 omega 6s to 1 omega 3
45
Linoleic acid
- precursor of?
- skin
- inflammation
- omega 6 fatty acid and serves as an arachidonic acid precursor which will be converted into prostaglandins and leukotrienes which are inflammatory
- A complex forms with linoleic acid to make skin impermeable to water
- Linoleic acid is also a neuronal fat precursor
46
alpha-linoleic acid
- use
- amount
- use of end products
- mostly for energy but can be converted to EPA and DHA
- The average person converts 5-10% of omega3 to EPA and DHA but some people who eat a lot of omega 3 can convert up to 20%
- EPA will turn into less inflammatory prostaglandins (eicosanoids) and DHA supports nerve function myelin sheath as well as retina function in the eye, also added to infant formulas to support brain development for the growing baby
47
Trans Fats
- Chemical structure
- why?
- Physical state
- Sources
- On nutrition label
- most common form in US
- exception
- Effects on health
- They've been transformed, take a polyunsaturated fat and turned it into a saturated fat by adding hydrogen to it
- increase shelf-life of foods because saturated fats are less susceptible to oxidation
- Solid at room temperature
- Fried foods/ processed foods
- called hydrogenated fats
- from partially hydrogenated vegetable oils
- conjugated linoleic acid (CLA) found in small amounts of grass-fed beef and dairy.
- strong increase of heart disease, increase in total cholesterol, lowers HDL (good cholesterol)
48
Oxidized Fats
- effect
- what should you do?
- smoke point
- what oils to use for cooking
- animal fats at high temp
- Oxidized LDL causing a lot of inflammation and cardiovascular disease by causing LDL to be recognized as foreign and provoke an inflammatory response in the body
- Try to keep fats air tight so they are not exposed to oxygen and keep away from light and heat-- Don't store vegetable oils right next to the stovetop because radiant heat can come off of the stove
- If your oil starts to smoke at a lower temperature, it affects cooking because you will need to cook at a low enough temperature to avoid making it smoke so companies filter out smoking impurities from the oil however "impurities" are good for you such as vitamins, plant nutrients, and antioxidants.
- natural oils that can withstand higher temperatures such as avocado oil, Ghee and almond oil
- cooking animal fats at high heats creates a lot of carcinogenic biproducts like heterocyclic amines
49
Counseling patients on fats
- Saturated fats
- Monounsaturated fats
- Polyunsaturated fats
- advise patients to use coconut oil and high-quality dairy
- advise patients to use extra-virgin olive oil and nuts
- Polyunsaturated fats- Vegetable sources of ALA such as flax, chia seeds and walnuts and salmon, mackerel, anchovies, sardines, herring for omega 3
- stay away from Trans fats as well as very-long-chain and long-chain saturated fats from animal products
50
Amino acid structure
- which part is toxic? what happens to the remnant?
- how does a cell use the carbon skeleton
- The amine group and we don’t want to accumulate that part; we use the carbon skeleton
- used for glucogenesis (acetyl-CoA) and ketogenesis; which will then produce energy or glucose through gluconeogenesis
51
- difference between essential and non-essential Amino Acid?
- semi-essential AA
- Why does the body choose to make some AA and some from diet?
- Ex. glycine and glutamine
- Essential are not synthesized in the body we get them from diet.
- Semi-essential AA: synthesized in the body as part of a metabolic cycle but in very small amount so you will still have to supplement it or take it via diet.
- The body makes non-essential AA because it uses it to produce other things in the body and the body has to have control over that so the body makes it itself.
- Glycine is used in purine and pyrimidine synthesis and synthesizing the pyrol ring in Heme
- Glutamine is the source of energy for the enterocytes of the small intestine and it is considered a conditional essential amino acids and sometimes used as a supplement for GI problems.
52
Amino Acid metabolism
- What are the sources of Amino Acids in the cell?
- Do we synthesize AA in the body from scratch?
- What is the fate of amino acids?
- Name some AA that are used in Purine and Pyrimidine synthesis?
- Glucogenic AA
- Ketogenic AA
- We get them from diet, proteins are taken in from diet and assimilated as AA.
- Yes, we do. A lot of the intermediates of TCA and glycolysis are used for synthesis of AA. Also proteolysis from muscle breakdown gives amino acids
- The amine group gets out because it is toxic, the carbon skeleton of the AA is used to make glucose or energy and also used in making purines and pyrimidines
- Glycine Glutamine, aspartate,
- carbon skeleton will make glucose from AA through gluconeogenesis
- Lysine and Leucine
53
Biosynthesis of Amino Acids
- PEP
- 3- phosphoglycerate
- Pyruvate
- Oxaloacetate --leads to--which can
- Alpha Ketoglutarate
- PEP makes aromatic amino acids; pyruvate to oxaloacetate and then PEP through carboxykinase
- 3- phosphoglycerate makes serine, cysteine and glycine which are hydrophobic
- Pyruvate will make alanine which is the principal Glucogenic AA , valine and Leucine.
- Transamination of Oxaloacetate in TCA cycle will make aspartate.
- Aspartate will then go through dehydrogenation and another phosphorylation step to form methionine, threonine and lysine.
- Lysine can further form Isoleucine.
- Alpha Ketoglutarate can by adding an amine group to it be converted to glutamate.
54
Why is Alanine the principal Glucogenic AA?
Because if you transaminase Alanine, it will be converted into pyruvate in a one step process so it is much easier for the cell to get energy from Alanine- pyruvate - TCA-ETC when it needs energy. Valine and Leucine on the other hand require a couple more steps to back to pyruvate.
55
PRPP
is the phosphorylated 5-carbon sugar which is involved in the formation of purine and pyrimidine. It can also be used to make histidine but it is a complicated process.
56
Catabolism of Amino Acids
- When there is too much AA the body will convert all these TCA intermediates and once you form alpha ketoglutarate then succinyl-CoA, they can go through TCA, come to oxaloacetate.
- Your principal ketogenic AA are Leucine and Isoleucine which will produce acetyl-CoA.
- If you look at the chart how will you classify the AA? Ketogenic, glucogenic or both- Most of them are both.
57
Fed and Fasting states
- fed state
- How does AA form Lipid?
- AA to glucose
- fasting state
- In the Fed state, Insulin an anabolic enzyme will promote the synthesis of AA to synthesize protiens and the excess which doesn’t make protiens can be used to make lipids.
- If we have ketogenic AA making a lot of acetyl-CoA, then there will high amount of citrate from Acetyl-CoA, then Citrate comes out and helps in the synthesis of Fat in the cytoplasm. Once the endogenous fat are synthesized they are packaged in VLDL and sent out into the blood.
- gluconeogenesis most of it released as energy but some is stored as glycogen.
- In the fasting state, glucagon, epi and cortisol are active. Glucagon will stimulate the breakdown of protien into AA. It will promote a lot of glucogenesis in the liver and urea production.
58
Nitrogen Balance
- How can you define nitrogen balance?
- Neutral
- Positive
- When will the body want more Nitrogen?
- Negative
- It is the balance between protein ingestion and excretion.
- when there is a balance between ingestion and excretion
- is when intake is greater than excretion.
- during pregnancy, growth phase and trauma.
- when there is more excretion than ingestion and can happen during malnutrition
59
Trans-ammination
- what is it?
- What is the enzyme called?
- important transaminase that are present in the liver
- coenzyme
- What happens
- reaction that removes the amine group from the amino acid-- takes amino acid and alpha ketogluterate and converts it to alpha keto acid and glutamate
- Transaminase
- AST, ALT,
- Vit. B6(pyridoxine); deficiency in pyridoxine phosphate will slow down urea cycle because AA are not getting transaminated and therefore the ammonia is not making it into the liver
60
What will the glutamate do with the Amine group, how will it get it to the liver since it is formed in the periphery ?
- The glutamate can go to the urea cycle through two routes.
- It can go do a second transamination where the amine group of the glutamate will be accepted by oxaloacetate and form aspartate. This aspartate will go into the urea cycle in a 3rd reaction and donate this amine group to the formation of urea.
- The second is that the glutamate can undergo oxidation ( glutamate dehydrogenase oxidizes the glutamate) and release an ammonium ion which will go into the first reaction of the urea cycle.
- Remember each urea needs two amine groups, one comes in as an aspartate and the other comes in as an ammonium ion.
- Does glutamate only form in the liver cells?- NO, it can form in peripheral muscles anywhere, so those glutamate that are formed in the peripheral cells has to make a long journey through the blood into the liver.
61
What is the fate of the glutamate formed in the periphery?
- what happens once formed?
- what other AA can do that?
- will receive another amine group through the action of glutamine synthetase from the peripheral cell to form glutamine. Glutamate is acidic amino acid and glutamine is the amide form.
- After glutamine is formed it will be released in the blood.
- Alanine
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Why don’t we want to release Glutamate into the blood like glutamine?
- what happens when it gets to liver?
- what will it form? how?
- Glutamate is acidic so when released into blood it will drop the PH so you want to convert it to glutamine which is neutral.
- When glutamine gets to the liver, glutaminase will convert it back to glutamate by removing one of its amine groups. The Glutamate will also drop one of its amine groups forming alpha ketogluterate which can be reused. The amine groups will then go into the first reaction of the urea cycle.
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Two ways to get amine into urea cycle?
could come directly from oxidation of glutamate or it can come from glutamine as well.
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Alanine
- function
- how is it made?
- travel to liver? what happens when it gets there?
- transport of nitrogen from muscle cells.
- Pyruvate can take an amine group from glutamate and convert it into Alanine.
- Alanine comes out into the blood goes to the liver. When it gets to the liver it will be converted back to pyruvate and pyruvate is then going to go into gluconeogenesis to form glucose. It will also drop the nitrogen which will go into the urea cycle.
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Urea cycle
- where does it happen?
- starting material?
- what is final product? fate?
- high amount in blood?
- occurs in the mito of the hepatocytes
- bicarbonate and ammonium ion which is coming from glutamate, glutamine or alanine
- urea; comes out in blood gets into kidneys and gets eliminated through urine
- kidney malfunctioning
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Regulation- CPS1
- regular regulation
- allosteric stimulator
- glucagon
- Substrate availability upregulates it.
- N-actylglutamate ( NAG) is formed from glutamate and acetyl-CoA and is an allosteric stimulator of CPS1 .
- NAG is activated by glucagon-- because trying to make glucose from the glucogenic skeletons of AA
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Suppose someone has a malfunctioning liver, what will accumulate in the liver?
- what is the result of this?
- what are consequences of the result?
- how do neurons compensate?
- effects of compensation (alphaketogluterate level, glutamine, glutamate)
- Urea cycle will slow down so ammonia will accumulate, which will leak out of liver into blood stream
- increase PH which will convert the ammonium ion into ammonia which is toxic.
- High amount of ammonia build up in the blood is called hyperammonemia and can cross the blood bran barrier and get into the neurons and astrocytes.
- The alpha ketogluterate in the neurons will accept the amine group from ammonia to make a lot of glutamate. Another amine can be added to glutamate making glutamine.
- The alpha ketogluterate levels are going to go down which is going to slow down TCA cycle, low ATP production in neurons.
- Also, glutamine leads to mitochondrial permeability which affects neuronal function.
- since glutamate is being converted to glutamine then there is low glutamate which normally acts as a neurotransmitter and helps in production of GABA, so neuron function will go down and that will lead to neurological symptoms in patient like Hepatic encephalopathy.
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Build up if ammonia?
liver malfunctioning
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Use of AA
- tyrosine
- phenylalanine
- Glutamate
- Tryptophan
- Histidine
- makes DOPA, epi, norepi, melanin, T3/4
- makes tyrosine through phenylalanine hydroxylase.
- neurotransmitter is also used in making GABA
- used in making serotonin
- can be decarboxylated to make histamine which is part of the immune system
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Phenylketonuria (PKU)
- what is it?
- dietary?
- what happens to products?
- treatment?
- mutation in phenylalanine hydroxylase leads to accumulation of phenylalanine.
- phenylalanine that is coming from dietary sources is not being converted to tyrosine so there is accumulation of phenylalanine and deficiency in tyrosine.
- since tyrosine makes DOPA, epinephrine, melanin and norepinephrine, the patient will be deficient in these as well. So deficiency in neurotransmitters, and proteins production will be down too.
- decreasing food high in phenylalanine and supplement with tyrosene.
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Alkaptonuria
| - causes?
- In the third reaction of phenylalanine tyrosene metabolic pathway the product Homogentisic acid accumulates because Homogentisate 1,2 dioxygenase is deficient
- Homogentisic acid is eliminated in urine where it gets oxidized and changes the color of the urine to black.
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Maple syrup Disease
- three amino acids involved, type?
- enzyme affected? what does it normally do?
- how does this disease affect the normal pathway? toxic effects affect?
- age of dx?
- why the name?
- sxs?
- Isoleucine, leucine and valine; essential and have a branched structure.
- branched chain alpha ketoacid dehydrogenase: It is a mitochondrial enzyme that metabolizes high amounts of Isoleucine, leucine and valine into succinyl-CoA then propynyl -CoA which will come into TCA and form acetoacetate which then can produce acetyl-coA and help in energy production.
- one or more of the enzyme componenets is not working so a lot of toxic intermediates that are produced when leucine, isoleucine and valine are broken down will accumulate because they cannot be metabolized all the way to succinyl-CoA and propynyl -CoA . These accumulated intermediates are toxic to the neurons.
- right after birth.
- because the urine is sweet smelling.
- neurological symptoms: baby doesn’t feed well, vomits and may go into a coma if not treated.
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Cystinuria
- what is cystine? where is it found?
- what is this disease?
- Cysteine is found in folded protiens because it forms disulfide bonds.
- lots of cysteine in the urine because the kidney is not re-absorbing it so it gets converted to cystine by oxidation and precipitate as crystals in the urine.
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Proteins
| - recommended dietary allowance
- 0.8 grams/ kilogram of body weight
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Amino Acid distribution and quality
- what do we do with excess?
- what essential AA should we be worried about getting? where can we find them?
- complementary protein consumption
- how could you be deficient in AA (3)?
- it can be stored
- lysine (Grains)
- methionine (beans)
- Balanced meal of plant, fruits, and meats should get you AA you need
- someone who is dietarily deficient; not eating balanced or varied diet, not eating any meat all, they're not eating much food to begin with
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Protein requirements for
- older
- pregnant women
- children
- athletes
- older: 1-1.2g/kg
- prego: 1.1 g/ kg
- child: 1.05g/ kg
- mod intense: 1.2g/kg; elite endurance: 1.7g/kg
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Protein: animal vs fat
- health effects of animal protein
- health effects of plant protein
- health effect subing plant for animal
- animal: risk of death is not high but there is higher risk of stroke and type II diabetes bc there is higher amount of long chain saturated fats
- plant: lower mortality but there is difference in energy increment (not by much)
- lower mortality especially when it comes to processed meat
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Risk of high protein diet?
- exposure to nitrates/nitrites
- build up of ammonia: If there's way too much protein and overloads liver, you can't convert all of it from nitrogen to urea
- more weight gain over time: protein can be turned into fat
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Xenobiotics
| - meaning of "xeno"
- stranger, so things that are foreign substances that enter your body.
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biotransformation
- where?
- what do they use?
- smooth ER of liver
| - Cytochrome P450
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First pass metabolism
- what is it? ex?
- what happens to [ ]
- effect of bioavailability
- oral drug given orally and enters the hepatic circulation
- decreases
- decreases
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Phases of Cytochrome P450
- what is it?
- phases
- what's the point
- Cytochromes function as electron transfer agents in many metabolic pathways, especially cellular respiration.
- Phase I: Primarily Cytochrome P450 (34A, 2D6): used for metabolism for more than 75% of all drugs; enzymes doing things like oxidation, reduction, hydrolysis
- phase II, it's the UGT (Glucuronic acid); conjugation reactions
- make it hydrophilic so it gets trapped bc we want to eliminate it; combining them with different acids and things we have in our body to make it more polar/ionized so that it gets trapped in urine and eliminated.
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Adverse drug reaction
- importance?
- 1A2-- drug substrates
- 2C9-- drug substrates
- 2D6-- drug substrates
- 100,000 deaths per year and 7% hospital admissions
- Acetaminophen, Alosteron, Warfarin--inducers (environmental factors like grilled meat, vegetables, smoking) and inhibitors (H2 antagonists)
- Alosteron, Diclofenac, Cannabinoid agonists (antiemetic), indomethacin, ibuprofen-- inhibitors: Antifungals.
- Opioids
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St. Johns wort and vinblastine
- substrates
- enzyme
- response
- effect
- Substrate: Vinblastine, St. John's Wort
- 3A4 is enzyme
- St. John's Wort is inducer: this means you're increasing the expression of the enzyme and more enzyme being made so more of the drug is being metabolized.
- If you metabolize the Vinblastine more than you normally would, you would expect the concentration would be decreased and the therapeutic effect is decreased, so anti cancer effect would potentially be less effective
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grapefruit juice and clarithromycin
- substrates
- adverse interaction
- toxicities
???
- 34A substrates
- grapefruit is an inhibitor, concentration of clarithromycin increases in plasma, and with too much drug concentration in plasma, toxicities and adverse effects occur. Bc now you have high enough concentrations where these drugs are not only interacting with their site of action, but now they can get promiscuous ;-) and go places they're not supposed to.
So you'd need to realize this is why knowing the toxicities is really important.
- CNS and GI issues
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Codeine and breast milk
- what is codeine?
- what happened to amount?
- what happened to baby?
- tox?
- Codeine Is a prodrug.
- ultra metabolizer converts codeine to its active metabolite faster than average person
- excess morphine go through milk to child and causing his symptoms.
- Abdominal pain
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mucosal surfaces
| - important function?
- important site of communication
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mucins
| - properties
- huge polypeptide chain
- rich in S&T
- siliac acid on glycans binds soluble effector molecules
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Importance of sialic acid
| -
- negative charged sialic acid which is found in mucins and glycans will bind the positively charged defensins and IgA
- defensins passively keep pathogens from infection and can destroy the invading pathogen
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What happens when patient with agammglubulinemia takes prophylactic antibiotics?
- slow wound healing because killing off the commensal bacteria which causes a decreased capacity to produce Vit k
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Changes to immune system without microbiota
- anatomical
- immunological effect
- benefit of a longer small intestine
- enlarged cecum, longer smaller intestine, underdeveloped mesenteric lymph nodes, underdeveloped peyers patches, fewer isolated lymph follicles, smaller spleen
- reduction in IgA, systemic T-cell numbers, reduced cytotoxicity of CD8, impaired lymphocyte homing, reduced number of lymphocytes, reduced ability of neutrophils to kill bacteria
- More time & surface area for digestion & absorption of nutrients that the microbiota would normally help you w/.
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Why do bubble people not have gut microbiota?
- He lives in a sterile environment. If you are living in a sterile environment you are not gonna have the ability to colonize gut bacteria and those gut bacteria have imp roles. One of those roles is development of out immune response. So during childhood, the human body and the immune system grow and mature together in the context of your commensal bacteria
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How quickly do they colonize your gut?
- Happens almost immediately right after birth.
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Polio vaccine
- in endemic area? why?
- in US
- what happens without tonsils?
- oral: which is live; with inactivated you can still get infected, you just won't have symptoms but you can still spread disease
- sub cut: inactivated
- response to oral polio vaccine is impaired bc you cant make secretory IgA which is critical for this vaccine-- so wont produce a protective amount of secretory IgA OR they can get sick from it
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lymphoid tissue found in the large intestine
- isolated lymphoid follicles which contain B cells
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lymphoid tissue found in small intestine?
- peyer's patches and isolated lymphoid follicles.
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what is in peyers patches?
B cells, T cells, and APCs (dendritic cells & macrophages)
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enterocyte initiation of inflamm response
- use?
- rate?
- effector cells?
- TLR, NLRs that induce an inflammatory response.
- very rapid response because of 2 day turnover rate-- enterocytes that were responding in an inflammatory way are usually gone in 48H
- are already activated, and vast majority of them are activated against the commensal bacteria to keep them in check.
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roles of M cells in mucosal immune response
| -disadvantage?
- delivering antigens from gut to the inductive tissue
| - rapid transport: pulling in antigen so fast that the induction cells don’t have time to engulf it and process it all.
100
cells in inductive tissues
- lymphocytes (CD4 and 8 cells and plasma cells)
| - dendritic cells
101
follicle associated epithelium
| - why is it defended poorly?
- no goblet or pannus cells (make defensin) and no crypts
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how do lymphocytes stay in middle of enterocytes?
- receptor?
- gradient they follow? with what receptor?
- ecadherin binds to Alpha e:beta 7 receptor allows them to intercalate into the enterocytes
- CCL25 using CCR9 receptors (this leads them to the enterocyte)
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Important role in mucosal immune responses
- Do NOT:
- have:
- lack:
- APC?
- function?
- respond to infection by secreting inflammatory cytokines OR give a respiratory burst in response to inflammatory cytokines made by other cells
- MHC II molecules
- B7 co-stimulators and the capacity to make the cytokines needed to activate and expand naive T cells: IL-1, IL-10, IL-12, IL-21, IL-22, and IL-23
- no; and cannot initiate adaptive immune responses
- 1st line of defense; proficient at phagocytosis and the elimination of microorganisms and apoptotic dying cells
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Gastrointestinal tract
- how long?
- bacterial burden
- 9m long
| - increases as you go down the GIT and reaches its peak in the colon
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Isotypes of IgA
| - where is it found?
- IgA1: longer, more flexible hinge region (26 AA). More susceptible to cleavage by proteases that are utilized by commensal bacteria, in this case E. Coli.
- IgA2: has a shorter, stronger hinge region (13 AA). It's bonded covalently with a carbohydrate component, so it's more resistant to protease cleavage.
- Upper GI will have IgA1 and colon has IgA2
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Selective IgA deficiency
- Cause
- symptoms
- susceptible
- compensation
- defective isotype switching from IgM to IgA
- These pts are generally healthy but susceptible to bacterial infections of the lungs, and to intestinal infection by Giardia lamblia
- Increased secretion of pentameric IgM compensates for the absence of secretory IgA
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IgM
particularly important, because it has the J chain that interacts with the poly-Ig receptor and so can be secreted at mucosal surfaces, like IgA.
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cytokine function
- IL-4
- IL-9
- IL- 13
- IL 25
- 4: induces IgE response
- 9: importnt for mucousal mast cell hyperplasia
- 13: induces goblet cell formation to help us produce more mucus
- IL25: induces IL-4, IL-5, IL-14
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Organisms associated with non-bloody diarrhea and the absence of fever
- stool sample
- acid fast
- cryptosporidium, cyclospora, giardia
- looking for parasites
- cryptosporidium stains acid fast
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giardia
- trophozoite version
- Axostyle
- cyst formation
- treatment
- trophozoite version: smiles back at you; you're looking for flagella inside
- Axostyle: line that goes all the way down the body.
- cyst formation: should see 2-4 nuclei
- Metronidazole: Requires reductive activation from the microorganism. The parasite itself has electron transport components that allow it to donate protons and allow the prodrug to become active. These radical forms of the molecule allow it to cause DNA inhibition.
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Entamoeba
- Distinguishing feature
- cyst form
- Tx
- at the top you see the ingested RBC (RBC meal) and only 1 nuclei in trophozoite form
- there are more nuclei and the dark stained things are chromatoid bodies
- metronidazole
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cryptosporidium
- size
- stain
- tx
- 5-7 micrometers
- acid fast
- Aminoglycosides: They inhibit 30S ribosomal subunit
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Cyclospora
- Tx
- size
- TMP-SMX
| - 8-10 micrometers
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Chinese liver fluke
- where is this more common?
- Eggs
- korea
| - characterized by a distinct operculum with prominent shoulders & a tiny knob at the posterior pole
