AminoAcidMetabolism Flashcards
8 Dietary Essential Amino Acids + 2 other semi-essential amino acids
Phenylalanine, Valine, Tryptophan, Threonine, isoleucine, Methionine, Leucine, Lycine Histadine, Arginine (optimal growth)
Synthesis of Dietary Non-Essential Amino Acids - Alanine
amination of pyruvate
Synthesis of Dietary Non-Essential Amino Acids - Aspartate
amination of oxaoloacetate
Synthesis of Dietary Non-Essential Amino Acids - Asparagine
amidation of aspartate
Synthesis of Dietary Non-Essential Amino Acids - Cysteine
from Serine & homocysteine
Synthesis of Dietary Non-Essential Amino Acids - Glutamate
amination of alpha-ketoglutarate
Synthesis of Dietary Non-Essential Amino Acids - Glutamine
amidation of glutamate ( aminate carboxyl side chain)
Synthesis of Dietary Non-Essential Amino Acids - Glycine
from Serine
Synthesis of Dietary Non-Essential Amino Acids - Tyrosine
Hydroxylation of phenylalanine
Synthesis of Dietary Non-Essential Amino Acids - Proline
from gluatmate or ornithine (by a series of reactions)
Synthesis of Dietary Non-Essential Amino Acids - Serine
from 3-phosphoglycerate (glycolytic intermediate)
Glucogenic Amino Acids via pyruvate
alanine, cysteine, glycine, & serine
Glucogenic Amino Acids via alpha-ketoglutarate
arginine, glutamate, glutamine, histidine, proline
Glucogenic Amino Acids via oxaloacetate
aspartate & asparagine
Glucogenic Amino Acids via succinyl-CoA
methionine, threonine, & valine
Glucogenic & Ketogenic Amino Acids via succinyl-CoA & acetyl-CoA
Isoleucine
Glucogenic & Ketogenic Amino Acids via fumarate & acetyl-CoA
phenylalanine & tryosine
Glucogenic & Ketogenic Amino Acids via pyruvate & acetyl-CoA
tryptophan
Ketogenic Amino Acids via acetyl-CoA
leucine and lysine
Glucogenic Amino Acids
those amino acids whose metabolism yeilds an intermediate of the citric acid cycle or gluconeogenesis
in diabetic animal, metabolism of these amino acids will result in elevation of blood glucose levels
Ketogenic Amino Acids
those amino acids whose metabolism yeilds acetyl-CoA
in diabetic animal, metabolism of ketogenic amino acids will result in an elevation of circulating ketone bodies
Alanine aminotransferase (ALT)
alanine + alpha-ketoglutarate –> pyruvate + glutamate
reversalbe reaction but works in direction of glutamate synthesis (Nitrogen collector) from alanine
elevated levels lead to liver damage
Aspartate Aminotransferase (AST)
oxaolacetate + glutamate –> aspartate + alpha-ketoglutarate
exception to the rule= AST –> AST transfers amino group from glutamate to aspartate (used as the source of nitrogen in the urea cycle)
increase levels of AST in plasma –> sign of cardiac ischemia
Breakdown of Amino Acids
Transamination –> oxidative deamination
Synthesis of amino acids
Reductive amination –> transamination
Transamination
amino acid + alpha ketoglutarate –> keto acid + glutamate; the acceptor is alpha ketoglutarate to yeild keto acid and glutamate (glutamate is then subject to oxidative deamination in the reaction catalyzed by glutamate dehydrogenase)
Oxidative Deanimation
glutamate + NAD+ + H2O –> alpha ketoglutarate + NH3 + NADH + H+; uses glutamate dehydrogenase
Transaminase/Amino Transferase
uses pyridoxal phosphate (derived from Vitamin B) as coenzyme; the acceptor is pyruvate with the formation of alanine; exception is Aspartate aminotransferase
Urea Components
formed from a nitrogen of ammonia, nitrogen from aspartate, and a carbon from bicarbonate
Disease Associated with Urea Cycle
Less than optimal amount of enzymes for breakdown of ammonia–Synthesis of Urea – examples: Phenylketonuria, Maple Syrup Urine disease, alkaptonuria
Phenylketonuria
deficient in PHENYLALANINE HYDROXLASE or in atypical cases the defect is in dihydrobiopterin reductase; accumulation of phenylketones; excretion in the urine of phenylketones; mental retardation; light colored hair and skin (Scandanavia - first discovered bc blond, blue eyes) Reason for this light complexion is not alot of phenylalanine being transfered to tyrosine (formation of melanin); autosomal recessive condition; therapy=change of diet; can’t get ride of Phenylalanine from diet but need to limit for vital function (apartame is depeptide with phenylalanine)
Maple Syrup Urine Disease
deficiency in branched chain alpha-keto acid dehyrogenase, which is important for branched chain aa metabolism (leucine, Isoleucine, and valine) need to have some of these aa in diet but limited; odor of urine is like maple syrup; mental retardation
Alkaptonuria
deficient in homogentisate oxidase (an enzyme in catabolism of tyrosine); relatively benign-joint problems later in life; accumulation of homogenistic acid-which darkens the urine upon standing due to the acids polymerization; very rare but known for along time
Amino Acid Metabolites - Tyrosine
dopamine, epinephrine and norepinephrine, melanin (protection from UV rays), throxine and triidothyronine (thyroid hormones)
Amino Acid Metabolites - Tryptophan
Serotonin
Amino Acid Metabolites - Histidine
Histamine (thru simple decarboxylation)
Amino Acid Metabolites - Glutamate
gamma-amino butyrate (GABA)
Glycine and Argnine
Creatine (phosphorylated to make creatine phosphate, a high energy molecule)
Arginine (intermdeiate of Urea Cycle)
Polyamines (putrescine, spermidine and spermine) Nitric Oxide
Transfer of one carbon units:
the major carrier of methyl group is S-adenosylmethionine (SAM); involve a derivative of tetrahydrofolate serves as a carrier of one carbon units at the levels of methanol, formaldehye and formic acid(important in nucleotide synthesis); biotin is a carrier of carbon dioxide (pyruvate decarboxylase; fatty acid synthesis when forming malonyl CoA)
Sulfonamides
Structural analogs of p-aminobenzoic acid which is requried by bacteria for synthesis of tetrahydrofolic acid; used for bacteria chemotherapy
Methotrexate
Structural analog of dihydrofolate (intermediate in synthesis of tetrahydrofolate) inhibits the reduction of dihydrofolate to tetrahydrofolate; treatment of psoriasis; cancer chemotherapy
