Metabolism Flashcards
Metabolism that occurs in Mitochondria
beta-oxidation for FA oxidation, acetyl-CoA production, TCA cycle, oxudative phosphorylation
Metabolism in the Cytoplasm
Glycolysis, FA synthesis, HMP shunt, protein syn in rER, steroid syn in sER, cholesterol synthesis
Metabolism in both mitochondria and cytoplasm
Heme synthesis, Urea cycle, Gluconeogeneis
Kinase
Uses ATP to add high-energy phosphate group unto substrate
Phosphorylase
Adds inorganic phosphate onto substrate without using ATP
Phosphatase
removes phosphate group from substrate
Dehydrogenase
catalyzes oxidation-reduction reactions
Hydroxylase
adds hydroxyl group onto substrate
Carboxylase
Transfers CO2 groups with the help pf biotin
Mutase
Relocates a functional group within a molecule
ex is vitB12-dependent methylmalonyl-CoA mutase
Rate-determining enzyme for Glycolysis
Phosphofructokinase
inhibited by ATP and citrate
Rate-determining enzyme for Gluconeogenesis
Fructose-1,6-Bisphosphatase
inhibited by AMP and F2,6BP
Rate-determining enzyme for TCA cycle
isocitrate dehydrogenase
inhibited by ATP and NADH
Rate-determining enzyme for Glycogenesis
Glycogen Synthase
inhibited by epinephrine and glucagon
Rate-determining enzyme for Glycogenolysis
Glycogen Phosphorylase
inhibited by G6P, insulin and ATP
Rate-determining enzyme for HMP shunt
G6PD
inhibited by NADPH
Rate-determining enzyme for de novo pyrimidine synthesis
Carbamoyl phosphate synthetase II or CPSII
Rate-determining enzyme for de novo purine synthesis
Glutamine-phosphoribosylpyrophosphate (PRPP) amidotransferase
inhibited by AMP, IMP, GMP
Rate-determining enzyme for urea cycle
Carbamoyl phosphate synthetase I (CPSI)
Activated by N-acetylglutamate
Rate-determining enzyme for FA synthesis
Carnitine acyltransferase I
inhibited by malonyl-CoA
Rate-determining enzyme for Ketogenesis
HMG-CoA synthase
Rate-determining enzyme for Cholesterol Synthesis
HMG-CoA reductase
inhibited by glucagon and cholesterol
activated by insulin and thyroxine
Galactokinase
galactose → galactose-1-phosphate
Galactose-1-phosphate uridyltransferase
galactose-1-phosphate → glucose-1-phosphate
Hexokinase/Glucokinase
Glucose ↔ Glucose-6-P
G6PD
Glucose-6-P→ 6-phosphogluonolactone
HMP shunt
lack of this causes von Gierke’s
Phosphofructokinase
rate limiting step in glycolysis
makes fructose-6-P → F1,6P
to reverse this you would need F1,6Bisphosphatase which is rate limiting for gluconeogenesis
Adolase B
found in liver
A is in muscle
Pyruvate Kinase
PEP to pyruvate
Pyruvate dehydrogenase
requires thiamine cofactor TPP
Pyruvate → acetyl-CoA
Pyruvate Carboxylase
Requires Biotin
Pyruvate → Oxaloacetate
Isocitrate Dehydrogenase
Rate limiting step in TCA,
Isocitrate → alpha-ketoglutarate
Ornithine Transcarbamylase
Requires TTP
alpha-ketoglutarate → succinyl-CoA
ATP production in the heart and liver
net 32 ATP, malate-aspartate shittle
ATP production in the muscle
net 30 ATP, uses glycerol-3-phosphate shuttle
ATP production in Anaerobic Glycolysis
net 2 ATP per glucose molecule
Phosphoryl groups
carried by ATP
Electrons
carried by NADH, NADPH, FADH2
Acyl groups
carried by CoA, lipoamide
CO2 carried by
Biotin
1 carbon units
carried by tetrahydrofolates
CH3 groups
carried by SAM
Aldehydes
Carried by TPP
Product of HMP Shunt
NADPH
Use of NADPH
anabolic processes like steroid and FA synthesis
respiratory burst
cytochrome P450 system
glutathione reductase
Low Km
High affinity
Low Vmax
Low capacity
Glucokinase
induced by insulin, high Km, found in liver and beta-cells of pancreas
Mutated in MODY
Glucokinase
hexokinase
Low Km, Low Vmax, in most tissues except liver and beta cells of pancreas
inhibited by glucose-6-P
Enzymes that require ATP in glycolysis
hexokinase/glucokinase
phosphofructokinase-1
Enzymes that produce ATP in glycolysis
Phosphoglycerate kinase
Pyruvate Kinase
Purely ketogenic amino acids
Lysine and Leucine
Pyruvate dehydroxylase complex deficiency
causes a build up or pyruvate that gets shunted to lactate via LDH and alanine via ALT
neuro issues, lactic acidosis, increased serum alanine in infancy
Tx for Pyruvate dehydroxylase complex deficiency
increase ketogenic nutrients, high fat content of increase lysine and leucine
Complex I of ETC
uses NADH electrons and pumps out hydrogen into intermembrane space of mitochondria
inhibited by Rotenone
Complex II of ETC
uses FADH2 electons
succinate dehydroxynase
Complex III of ETC
take electrons from CoQ and pumps hydrogen into intermembrane space
inhibited by Antimycin A
Complex IV
takes electrons from cytochrome C, makes water
pumps hydrogen into the intermembrane space
inhibited by cyanide and CO
ATP synthase
makes ATP and pushes H into mitochondria matrix
inhibited by Oligomycin
Uncoupling Agents
2,4-Dinitophenol, aspirin, thermogenin in brown fat
increases permeability of mitochondrial membrane
decreases hydrogen gradient and increases oxygen consumption
products heat
Glucose-6-phosphatase
occurs in ER to make glucose
an irreversible enzyme
Odd-chain FA
yield 1 propionyl-CoA during metabolism, which can enter the TCA cycle as succinyl CoA
can also undergo gluconeogenesis
Even-chain FA
can’t produce glucose, only yield acetyl-CoA
Purpose of HMP Shunt
provides a source of NADPH which is required to reduce glutathione inside RBCs to prevent destruction and for FA and cholesterol biosynthesis
Sites of HMP Shunt
Lactating mammary glands, adrenal cortex for steroid syn, RBCs
Oxidative HMP shunt Enzyme
Glucose-6-dehydrogenase, rate limiting step the make G6P into 2NADPH, CO2, and ribulose-5-P
Nonoxidative HMP shunt enzyme
phosphopentose isomerase, transketolase (req B1)
makes ribulose5P into ribose5Pi, G3P and F6P
NADPH oxidase deficiency
chronic granulomatous disease
Steps of Oxidative Respiratory Burst
NADPH oxidase, Superoxide dismutase, myeloperoxidase, glutathione peroxidase (req selenium), glutathione reductase (req selenium), G6PD
Pyocyanin
P. aeruginosa tonxin that generates ROS to kill competing microbes
Lactoferrin
protein in secretory fluid and neutrophils that inhibits microbial growth viw iron chelation
Heinz Bodies
G6PD deficiency, precipitated and oxidized Hb
Bite Cells
G6PD deficiency,phagocytic removal of Heiz bodies by splenic macrophages
Agents that exacerbate G6PD deficiency
fava beans, sulfonamides, primaquine, antiTB drugs
they are oxidizing agents that lead to hemolytic anemia
G6PD deficiency genetics
X-linked recessive, most common human enzyme deficiency
primarily in blacks
Defect in fructokinase
Essential fructosuria
auto recessive, see fructose in blood and urine otherwise fairly benign
Hereditary deficiency in aldolase B
Fructose Intolerance - stay away from honey, juice and fruit
Autosomal recessive
Fructose-1-P accumulates
hypoglycemia, jaundice, cirrhosis, vomiting
infantile cataracts, failure to track objects, don’t develop a social smile
Galactokinase deficiency
galactitol accumulates
auto recessive
Classic Galactosemia
absence of galactose-1P uridyltransferase
galactitol accumulates in lens of eye
failure to thrive, jaundice, hepatomegaly, infantile cataracts, intellectual disability
E. coli sepsis
classic galactosemia can lead to neonatal E. coli sepsis
Areas with aldose reductase
Schwann cells, retina, kidneys
need NADPH to make slucose into sorbitol
Osmotic Diarrhea
Lactase deficiency
also gets bloating cramosm and flatulancea
Glucogenic Amino Acids
methionine, Valine, Histidine
Acidic Amino Acids
aspartic acid, glutamic acid
negatively charged at body’s pH
Basic Amino Acids
arginine, lysine, histidine
has no charge at body’s pH
Amino acids required during periods of growth
arginine and histidine
Amino Acids increased in histones which bind negatively charged DNA
Arginine and lysine
Ornithine Transcarbamylase
ornithine into citrulline
requires carbamoyl phsophatase
Arginase
makes arginine and H2O into urea to be excreted by kidneys
Amino Acids that transport ammonia
Alanine and Glutamate
Ammonia intoxication
tremor (asterixis), slurred speech, somnolence, vomiting, cerebral edeam and blurred vision
Too much ammonia inhibits
TCA cycle
Traps NH4+ in GI tract for excretion
Lactulose, used to tx hyperammonemia
Binds to amino acids in diet for excretion
Benzoate or Phenylbutyrate (tx hyperammonemia)
Required cofactor for carbamoyl phosphate synthetase I
N-acetylglutamate
N-acetylglutamate Deficiency
hyperammonemia (tremor, slurred speech, cerebral edema)
increased ornithine with normal urea cycle enzymes
increase orotic acid in blood and urine
Ornithine Transcarbamylase Deficiency
X-linked recessive, excess ammonia
tremor, slurred speech, cerebral edema
orotic acid is part of pyrimidine pathway
Use of SAM
NE → Epinephrine
makes melatonin
Tryptophan→ serotonin → melatonin
Amino acid for porphyrin/heme
Glycine
Amino Acid for GABA and Glutathione
Glutamate
Amino Acid for Creatine, Urea, Nitric Oxide
Arginine
Deficient in Phenylalanine hydroxylase
PKU
Deficient in Homogentisate oxidase
Alkaptonuria
degradative pathway of tyrosine to fumarate
Deficient in Tyrosinase
Albinism
Inhibited by Carbidopa
DOPA decarboxylase to inhibit DA production
musty body odor, fair skin, eczema
PKU (Auto recessive)
Avoid aspartame
PKU because it contains phenylalanin
Brown pigmented sclera, urine turns black on prolonged exposure to air
Alkaptonuria (ochronosis)
Cystathionine Synthase deficiency
Homocystinuria
Tx of Homocystinuria from cystathione synthase deficiency
decrease methionine, increase cysteine, increase B12 and folate in diet
Decreased affinity of cystathionine synthase for pyridoxal phosphate
Homocystinuria, tx with increase Vit B6 and cysteine
Homocysteine methyltransferase deficiency
Homocystinuria, tx with increase methionine in diet
Findings for homocystinuria
increase homocysteine in urine, dumb, osteoporosis, tall stature, kyphosis, lens subluxation (down and in), thrombosis, and atherosclerosis
Hexagonal Cystine Stones
Cystinuria
Tx K-citrate and acetazolamide
Urinary cyanide-nitroprusside test
Diagnostic for Cystinuria
Hereditary defect in Cystinuria
Auto recessive
renal PCT and intestinal AA transporter for Cysteine, Ornithine, Lysine and Arginine (COLA)
Branched Amino Acids
Maple Syrup Urine Disease
I Love Vermont Maple Syrup
Isoleucine, leucine and valine
Limit Dextran
1-4 residues remaining on a branch after glycogen phosphorylase has already shortened it
Von Gierke Disease
deficient in glucose-6-phosphatase, aut recessive
severe fasting hypoglycemia, increased blood lactate, increased glycogen in liver
Tx of Von Gierke Dx
frequent oral glucose/cornstarch
AVOID fructose and galactose
Cardiomyopathy early death glycogen storage dx
Pompe Disease, deficient in lysosomal alpha1,4-glucosidase
Cori Disease
Lack debranching enzyme alpha-1,6-glucosidase
fasting hypoglycemia
McArdle Disease
deficient in myophosphorylase, increase glycogen in muscle
problem with beginning of exercise
red urine with strenuous exerise
Muscle Carnitine Deficiency
muscle pain later with exercise because fatty acid oxidation is used AFTER glycogen for muscle energy
FA in muscle biopsy
deficient in alpha-galactosidase A
Fabry Disease X-linked recessive
Accum ceramide trihexoside
Fabry Disease
peripheral neuropathy of hands/feet, angiokeratomas, CV/renal disease
Fabry Disease X-linked recessive
crumpled tissue paper
Gaucher Disease, auto recessive
Accum Glucocerebroside
Gaucher Disease, auto recessive
Deficient in Glucocerebrosidase of beta-glucosidase
Gaucher Disease, auto recessive
Cherry-red spot on macula, foam cells
Niemann-Pick Disease, Auto recessive
Cherry-red spot on macula, lysosomes with onion skin
Tay-Sachs, Auto recessive
Deficient in Sphingomyelinase thus accumulate sphingomyelin
Niemann-Pick Disease, Auto recessive
hepatosplenomegaly, progressive neurodegen
Deficient in Hexosaminidase A and accumulates GM2 ganglioside
Tay-Sachs, Auto recessive
Progressive neurodegeneration
Globoid Cells
Krabbe Disease, Autosomal Recessive
Deficient in Galactocerebrosidase
Krabbe Disease, Autosomal Recessive
developmental delay, optic atrophy, periph neuropathy
Deficient in Arylsulfatase A
Metachromatic Leukodystrophy, autosomal recessive
accum cerebroside sulfate
Central and peripheral demyelination with ataxia and dementia
Metachromatic Leukodystrophy, autosomal recessive
accum cerebroside sulfate
Deficient in alpha-L-iduronidase
Autosomal recessive Hurler Disease
corneal clouding, gargoylism, airway obstruction, mucopolysaccharidoses
Autosomal recessive Hurler Disease
Deficiency in Iduronate sulfatase
Hunter Syndrome - X-linked recessive
No corneal clouding, aggressive behavior
Hypoketotic Hypoglycemia
Carnitine deficiency
inability to transfer LCFAs into the mitochondria
Ketone Bodies
Prolonged Starvation and Diabetic Ketoacidosis
Oxaloacetate is depleted for gluconeogenesis
Protein and Carbohydrates
4 kcal
Fat
9 kcal
Alcohol
7 kcal
Fed State (after a meal)
glycolysis and aerobic respiration
insulin stim storage of lipids, proteins and glycogen
Fasting (between meals)
glucagon, adrenaline stimulates use of fuel reserves
hepatic glycogenolysis(major)
FFA release from fat (minor)
Starvation (1-3days)
Blood glucose maintained by hepatic glycogenolysis, FFA from adipose, muscle and liver shift fuel from glucose to FFA
Glycogen Stores Depleted
After 1 day of starvation
Starvation (>3days)
Ketones major source of fuel for brain
Lecithin-cholesterol acyltransferase LCAT
esterfies 2/3 of palsma cholesterol
S/E of statins
Rhabdomyolysis and Hepatotoxicity
must check LFTs and Creatine Kinase levels
Pancreatic Lipase
degradation of dietary TGs in small intestine
Lipoprotein Lipase
degradation of TG circulating in chlyomicrons and VLDLs
found on vascular endothelial surface
Hepatic TG Lipase
degrades TG remaining on IDL
Hormone sensitive Lipaase
degrades TG stored in Adipocytes
ApoE
mediated remnant uptake
found on chylomicron, its remnant, VLDL, IDL and HDL
ApoA-I
Activates LCAT
on chylomicron and HDL
ApoC-II
LPL Cofactor
on chlymicron, VLDL and HDL
ApoB-48
Mediates Chylomicron Secretion
On chylomicron remnant and on Chylomircon
ApoB-100
Binds LDL-receptor
on VLDL, IDL, LDL
Transports cholesterol from liver to tissues
LDL
Transports cholesterol from periphery to liver
HDL
Composition of Lipoproteins
cholesterol, TGs, phospholipids
Fx of Chylomicron
Delivers dietary TG to peripheral tissue.
Delivers cholesterol to liver in form of chylomicron remnants
Fx of IDL
degraded VLDL, delivers TGs and cholesterol to liver
Fx of VLDL
delivers hepatic TGs to peripheral tissue, secreted by liver
Fx of HDL
acts as repository for apoC and ApeE which are needed for chylomicron and VLDL metabolism
alcohol increases synthesis, secreted from both liver and intestine
Increased Chyomicrons, TG and cholesterol in blood
Hyper-chylomicronemia
Autosomal recessive
LPL deficiency fo altered apoC-II, get eruptive/pruritic xanthomas
Hyper-chylomicronemia
Autosomal recessive
Increased LDL and cholesterol in blood
Type IIa, Autosomal Dominant
Familial Hypercholesterolemia
Absent fo defective LDL receptors
Type IIa, Autosomal Dominant
Familial Hypercholesterolemia
Accelerated atherosclerosis, Achilles xanthomas and corneal arcus
Type IIa, Autosomal Dominant
Familial Hypercholesterolemia
Increase VLDL and TG in blood
Type IV, Autosomal Dominant
Hyper-triglyceridemia
Overproduction of VLDL
Type IV, Autosomal Dominant
Hyper-triglyceridemia
Shaggy’s Best Friend
Scooby-Doo