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Nutrchem > Proteins > Flashcards

Proteins Flashcards

1
Q

What are some functions of proteins?

A
  • Movement
  • Structural proteins
  • transport
  • protect against infections
  • communication
  • Participate in and regulate metabolism
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2
Q

Why do we need to acquire proteins from the diet?

A
  • Maintain protein balance (replacement of obligate protein loss and for growth)
  • Essential amino acid supply
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3
Q

What is the primary structure of a protein?

A
  • Linear number and order (amino acids)
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4
Q

True or False

Secondary structure codes for proteins

why or why not

A

primary does, the create order for the genes

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5
Q

What determines secondary structure

A

Primary structure

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6
Q

What is the secondary structure of a protein?

A
  • Determines the conformation of a protein
  • B pleated sheets and A heli
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7
Q

What interactions maintains the structure of a secondary protein?

A
  • postive and negative charges
  • hydrogen bonds
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8
Q

What is teritary structure?

A

Addition folding of proteins because of R-groups, spatial arrangements of poly-peptide chains

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9
Q

What maintains the structure of a tertiary protein

A
  • Hydrophobic interactions
  • Van Der Waals
  • Hydrogen bonds
  • Ionic bonds
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10
Q

What is quarternary structure?

A
  • Interactions between poly-peptide chains
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11
Q

What are prostetic groups

A

Non protein componets

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12
Q

What are the 9 essential amino acids

A
  1. Histidine
  2. Isoleucine
  3. Leucine
  4. Threonine
  5. Lysine
  6. Methionine
  7. Phenylalanine
  8. Trytophan
  9. Valine
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13
Q

What amino acids are semi essential and what are they made from

A

Met make Cysteine
Phe makes tyrosine

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14
Q

Why would amino acids be conditionally essential

A
  • under-developed/ insufficient synthesis
  • Increased requirements (stress, surgery, injury)
  • decreased synthesis
  • defective synthesis (lacking enzyme)
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15
Q

First stage of protein digestion

(where, what)

A
  • occurs in the mouth and salivary glands
  • Mechanical
  • moistens protein rich food and mixes them with saliva
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16
Q

2nd stage of protein digestion

A
  • beginning of chemical digestion
  • Gastric juices release HCL and Pepsin
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17
Q

What is HCL effect on protein digestion

A
  • denatures proteins
  • Activates pepsiongen to pepsin
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18
Q

What is pepsin effect on protein digestion

A
  • breaksdown into smaller peptides and free AA
  • inhibits pepsinogen (precursor) synthesis
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19
Q

Third step of protein digestion

A
  • Pancreas and small intestine
  • CCK release and pancreatic juices
  • enzymes of stomach denatures (pH: 6-7)
  • inactive zymogens converted to active enzymes to breakdown proteins into di-, tri-, and oligo-peptides
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20
Q

What do polypeptides and AA stimulate the release of and where does this occur

A

-cck and pancreatic juices

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21
Q

List the steps in the zygmogen cascade

A
  1. Epthieal cells release CCK
  2. Pancreas acinar cells release inactive zygmogen enzymes
  3. Duodenal enterocyte releases enterodiase
  4. Enterodiase release activate tripsinigen to form trypsin
  5. Trypsin activates whole cascade to active enzymes
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22
Q

What are incretins

A

The stimulates an insulin response

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23
Q

What are the 2 important incretins?

A

Glucagon-like peptide 1 GLP-1
Glucose dependent insulintropic polypeptide GIP

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24
Q

How do DPP-4’s work on incretins

A

DPP’s inactivate enzymes release of incretins which increase insulin response and decrease glucagon response —> decreases blood sugar

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25
Q

Not all proteins are broken down by pancreas enzymes, how is this solved?

A

BB peptidases (originate in the enterocyte)

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26
Q

How are proteins absorbed/transported?

A

-Diet brings in proteins, it’s gets broken down by duodenal and pancreatic enzymes. Which leaves amino acids, di and tri peptides along with large peptide
-Amino acids are taken into the enterocyte by BB aa transport system and di/tri peptides are taken up by BB peptide transport system which go into the enterocyte and di/tri peptides are turned into amino acids via cytoplasmic peptidases which can be exported out via basolateral amino acid transporter system and di/tri peptides are exported out via basolateral peptide system

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27
Q

Describe the sodium dependent amino acid transporter

A
  • Na binds the the transporter, which increases the affinity for amino acid to bind
  • amino acids binds which causes a conformational changes and amino acid and amino acid move to the inside of the cell
  • Na/ k atpase then transports Na out of the cell
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28
Q

Where in the intestine is the majority of amino acids taken up?

A

In the jejunum

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29
Q

What impacts the rate of absorption in a protein

A
  • structure of the protein
  • charge of the protein
  • food matrix
  • essential vs nonessential
  • amino acid vs oilgopeptides
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30
Q

How does the small intestine change to regulate amino acid absorption?

A
  1. Change is absorbtion surface area
    - hypertrophy associated with obesity/ diabetes/ lactation pregnanci
  2. Gene expression on enterocyte
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31
Q

Why are intact proteins generally not absorbed

A
  1. BBM proteases
  2. Tight junctions
  3. There aren’t any transporters for it
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32
Q

How does colostrum help babies with protein digestion?

A
  • provides nutrients for growth
  • immunoglobulin for protection
  • growth factors for GI track to mature
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33
Q

What happens in celiac disease

A

Gliadin protein get thru tight junction which enters the blood stream and causes an immune response

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34
Q

What role does the enterocyte play in aa avaiblity and absorption

A
  1. Enterocyte absorb amino acids
  2. Can use them for energy
  3. Used for protein synthesis
  4. Intermediary metabolic conversion
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35
Q

Reason for protein malabsorption

A
  • Severe pancreatic dysfunction
  • intestinal resection
  • serve chronic malnutrition
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36
Q

Name the different fates of aa breakdown in the body

A
  1. Non protein nitrogenous compounds
  2. Protein synthesis
  3. Catabolism with excretion of nitrogenous chains
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37
Q

Describe the process of transamination

A

Keto acid turn into an amino acid and the amino acid turns into a keto acid
- keto acid is regenerated to be used again
- NH3 from amino acid is then combined with CO2 to be excreted

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38
Q

Glutamate + OAA produce what products , with which enzyme

A

Produces : alpha- ketoglutarate + aspartate
With AST

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39
Q

Glutamate + pyruvate produce what with what enzyme

A

ALT
Alpha ketoglutarate and alanine

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40
Q

Where is ALT mainly found?

A

In the liver

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41
Q

Where is AST mainly found

A

In the heart

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42
Q

What does a high ALT?

A

Liver disease

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43
Q

AST/ALT ratio increase, indicates what?

A

alcoholic hepatitis, cirrhosis

44
Q

What is the purpose of delamination?

A

provide NH3 for urea synthesis and alpha keto acids for a variety of reactions including energy production when needed

45
Q

What AA stimulates the synthesis of NAG

A

Arginine and Glutamate

46
Q

What increase the urea cycle

A

High protein diet and starvation

47
Q

What is ammonia toxicity

A

Free ammonia is produced during the catabolism of AAs as well as nucleic acids that causes a raise in pH and neurotoxicity

48
Q

What are gluconeogenic AA

A

Come primary from CAC or pyruvate, removes OAA from CAC therefore AA’s used as intermediates. are gluconeogenic

49
Q

What are ketogenic AA

A

Uses primarily ACoA acetoacetate
A. CoA can enter CAC if sufficient OAA therefore ketogenic

50
Q

Explain single AA substitution?

A

Single nucleotide is switched which causes a change in AA which can cause major changes

51
Q

Why is protein degradation important

A

Because it regulates protein abundance and gets rid of mutated proteins

52
Q

Describe the UPS system

A
  • Proteins to be degraded are ligated to ubiquitin (‘tagged’) in an ATP-requiring reaction
  • increase during pathological conditions
53
Q

Describe Autophagy-lysosomal pathway (ALP)

A
  • large scale breakdown for energy
  • cushion with a Lysome which causes a breakdown of stuff inside
54
Q

What does the UPS system breakdown?

A

Degrades damaged, abnormal, relocated proteins

55
Q

What are some diseases associated with a malfunctioning UPS system?

A

Alzheimer’s and CVD

56
Q

When would the ALP system be activated?

A
  • when in need of energy
  • infection
57
Q

What contributes to the flux rate of proteins?

A

Flux rate = Degradetion + excretion = synthesis + intake

58
Q

What are the 2 compartments in the protein turnover model?

A

Free A.A - A.A in blood, tissue, and cellular compartments
Body Protein - all tissue and circulating proteins

59
Q

What are the different components of N metabolism?

A

Protein turnover (protein synthesis and degradation) and nitrogen balance (N input and output)

60
Q

What generally impacts nitrogen balance?

A

Protein turnover

61
Q

Is protein turnover a futile cycle? Why or why not?

A

It it is, it’s energetically expensive (10-25% BMR, we are constantly breaking down and synthesizing)

62
Q

What processes is protein turnover useful for?

A
  1. Used for gluconeogenesis, mobilize aa for glucose source
  2. Meet nutritional and physiological needs
  3. Nitrogen excretion
  4. Replace lost or damaged proteins
63
Q

What is the main site of AA degradation and why

A

Liver, closely linked to urea cycle

64
Q

What are the 2nd most important tissues when it comes to AA degradation?

A

Muscles - branched aa
Small intestine - uses AA as fuels, glu, gin, asp

65
Q

What are AA used for?

A

To create other molecules that use C skeletons and out that towards the body’s needs

66
Q

Why is skeletal muscles not the primary storage organ for AA?

A
  • the have more than enough proteins for demands
  • have storage for gluconeogenic precursors
67
Q

When does uptake of AA’s occurs?

A

Once protein is ingested

68
Q

What metabolic processes does protein turnover support?

A

Gluconeogenesis and protein synthesis

69
Q

Why is there limited free amino acids floating around?

A

Because it’s toxic and could cause affect transporters into the brain

70
Q

What are some protein catabolic signals?

A

-glucagon, catacholeamine, glucocorticoids, thyroid hormone and cytokines

71
Q

Protein anabolic signals?

A

Insulin and AA

72
Q

What processes are active during the fed and fasted state of proteins

A

Gluconeogensis
Ureagenesis
AA oxidation

73
Q

What happens is you eat a ton of protein

A
  • protein increase = body tries to get rid of it by making glucose
  • produces both glucagon and insulin
74
Q

Rank proteins that have to highest turnover rate to the slowest turnover rate

A

Fastest: Regulatory proteins
Non regulatory proteins
Slowest: structural proteins

75
Q

What occurs during anaorxia and physical inactivity in regards to protein

A

Anorexia: lower protein intake
Physical inactivity: muscle protein dyshomeostasis
Leads to loss in lead body mass and physical performance —> Increase mortality morbidity and disability

76
Q

What is the consequence of hyper metabolism or inflammatory state

A

Muscle wasting

77
Q

How can you induce muscle hypertrophy/anabolism

A

Increased muscle stress= increase local protein synthesis
Increased Ingestion of AA = decreases protein degradation = some acute muscle synthesis

78
Q

Ear for protein

A

0.66

79
Q

RDA for protein

A

0.8

80
Q

AMDR for protein

A

10-35%

81
Q

What happen when there is insufficient energy and we consume protein

A

It is used for fuel rather that protein synthesis

82
Q

What cells are impacted the most by short term protein deficiencies

A

Cells with quick turnover rates

83
Q

What cells are impacted the most by long term protein deficiencies

A

All organs +immune system + GI + kidneys

84
Q

What plasma proteins are assessed for deficiency

A

Albumins and transferrins
- other factors could impact

85
Q

What rapidly growing tissues could help determine a protein deficiency

A

Skin - thin + pale
Hair - doesn’t grow + falls out + changes colour

86
Q

Marasmus

A
  • Energy and protein deficiency
  • Muscle wasting, subcutaneous fat loss, growth retardation
  • Diet lacking in calories & protein likely also lacking in micronutrients & essential fatty acids
87
Q

Kwashiorkor

A
  • just protein deficiency
  • Growth retardation, edema, swollen abdomen, fatty liver, skin & hair changes, anemia, diarrhea
  • Causes:” decreased Synthesis of enzymes (lipid transport), hypoalbuminemia
88
Q

Which leads to more mortality marasmus or kwashiorkor

A
  • kwashiorkor
  • Hypoalbuminemia leads to defects in body fluid homoeostasis and edema, and deficiencies in apoB-lipoprotein synthesis to a fatty liver
89
Q

Short term effects of high protein diets?

A

weight loss, calcium loss, ketoacidosis

90
Q

Why is dietary protein required

A

To provide nitrogen for despensibile AA

91
Q

What are the different properties of protein quality

A
  • AA pattern or score
  • degestibility ( hydrolysis and availability of AA
92
Q

What AA is degraded by Maillard reaction?

A

Lys

93
Q

What aa is degraded by heat damage

A

Met, try

94
Q

What is the difference between true digestibility and appearent digestibility?

A

Da, fraction of amino acids that is absorbed (accounted for ingestion and fecal excretion)
Dt is counted for endogenous losses

95
Q

Why is protein digestibility in plant sources low?

A
  • proteins may be encapsulated in cell wall and we cannot degest that
96
Q

What impacts AA avaibility in food?

A
  • food processing and storage
  • heat can modify and degrade
  • Treat with strong acids
97
Q

Limiting AA definition

A

Most defieceint AA has relative to its requirment

98
Q

How do you calculate the PDCAAS

A

= AA score x Digestibility

99
Q

What are the possible inadequacies of a vegan diet?

A
  • protein
  • Fe, B12, Zn –> meat and eggs
  • Ca. Vit D, Riboflavin –> dairy products
100
Q

Benefits of a vegetarian diet

A
  • maintaince of weight
  • decreased blood pressure
  • ## Decrease CHD and T2D risk
101
Q

what amino acids dont participate in transamination

A

Lys, thr, pro

102
Q

what is deamination

A
  • liberation of free ammonia from the aa coupled with oxidation
103
Q

Where does deamination occur

A

liver and kidneys

104
Q

What the purpose of deamination

A

Provide NH3 for urea and A-ketoacids for a variety of reactions

105
Q

What stimulates the synthesis of NAG

A

arginine and glutamate

106
Q

What increases the urea cycle

A
  • high protein diet
  • Early starvation (proteins are degraded, C’c used for energy, increased N output and if N does not get excreted then increase free ammonia and increase toxicity
107
Q

Describe the glucose alanine cycle

A
  1. Ala is formed in the muscle from transamination with gluamate (Leucine is generated from transamination) from pyruvate
  2. Ala travels thru the blood to the liver
  3. In the liver, Ala travels into the blood to the liver
  4. ALA is transaminated to A-KG from pyruvate
  5. Pyruvate is converted back to glucose
  6. Glucose is release from liver into the blood and uptake by tissue for energy

Nutrchem (7 decks)

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