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MBC - Lecture 42

Biosynthesis and Turnover of Amino Acids (Douglas)

QuestionAnswer
Lecture 42 Biosynthesis and Turnover of Amino Acids
___ and ___ are ketogenic only amino acids. Leucine and lysine
___ and ___ are non-essential amino acids that require essential precursors. Tyrosine and tryptophan
Sulfur in cysteine is derived from ___. methionine
Urea cycle intermediates in the intestine and kidney are converted to ___ in the ___. arginine in the kidney
Glutamate is reduced to ___ using ATP and NADH. glutamic semialdehyde
Glutamic semialdehyde is formed from ___ by transamination. ornithine
Ornithine is a precursor of ___, ___, and ___. citrulline, arginine, and proline
Glutamic semialdehyde spontaneously cyclizes to ___. proline
___ is formed from 3-phosphoglycerate by aminotransferase and phosphatase. Serine
Glycine is formed from ___ by hydrolysis and transfer of methyl group to ___. serine, tetrahydrofolate
Serine Hydroxymethyl Transferase Catalyze interconversion of glycine and serine from threonine
Pyridoxal Phosphate Cofactor used in transaminations and reactions requiring amino transfer
Tetrahydrofolate Folate or vitamin B12, cofactor involved in C1 transfers
Tetrahydrobiopterin Vitamin BH4, cofactor involved in ring hydroxylations
Synthesis of cysteine requires condensation of ___ and ___. homocysteine and serine
Cysteine breakdown to ___ involves ___, ___, and ___. pyruvate involves oxidation, desulfation, and transamination
Causes of homocysteinuria: defective cystathionine synthetase or low B12/FH4/folate levels preventing remethylation of homocysteine
Histidine metabolism to glutamate is ___. unidirectional
Role of glutamate in amino acid biosynthesis is to transport ___ to and from ___ in the ___. carbons to and from glucose in the liver
Glutamate carbons from ___ are not from glucose. histidine
Excess ornithine is transaminated to ___, which is oxidized to ___. glutamate semialdehyde, glutamate
___ and ___ are strictly ketogenic (non-glucogenic). Leucine and lysine
Threonine is metabolized to ___, ___, ___, and ___. acetyl-CoA, glycine, pyruvate, and propionyl-CoA
Propionyl-CoA can be metabolized to ___. succinyl-CoA
Glutamate Dehydrogenase (GDH) Catalyzes reversible deamination of glutamate to a-ketoglutarate in the liver, using NAD+/NADP+ as a cofactor
The major route of glycine metabolism by glycine cleavage enzyme produces ___ and ___, and formation of ___. CO2 and NH4, and formation of methylene tetrahydrofolate
Defects in glycine cleavage enzyme pathway results in ___ and ___. nonketotic hyperglycinemia and glycine encephalopathy
Glycine degradation by ___ leads to glyoxylate then ___. d-amino acid oxidase, oxalate
Oxalate readily forms precipitates with ___ in kidneys to form ___. calcium, kidney stones
Serine metabolism to 3-phosphoglycerate is not a ___ of ___. reversal of serine synthesis
Serine Dehydratase Pyridoxal phosphate containing enzyme that converts serine to pyruvate
Synthesis of S-adenosylmethionine (AdoMet) is from ___ and ___. methionine and ATP
Homocysteine Methyl Transferase Catalyzes resynthesis of methionine from homocysteine, requires vitamin B12 1C addition
Homocysteine has only one ___ route. degradation
Methionine conversion (homocysteine degradation) produces ___. succinyl-CoA
Homocysteinuria Defective cystathionine synthase or B6 deficiency
Lysine is strictly ___, producing ___ when degraded. ketogenic, acetoacetyl-CoA
Branched chain amino acids (BCAA) make up for ___% of protein content. 25%
Branched chain a-keto acids are oxidatively decarboxylated, similar to ___. pyruvate dehydrogenase
Branched chain amino acids oxidized during fasting produces ___ and ___. energy and glutamine
Glutamine and alanine transport ___% of amino acid nitrogen. 50%
Phenylalanine and tyrosine share a common ___. degradation pathway
Phenylketonuria (PKU) results from defects in ___. phenylalanine dehydroxylase
BH4 is used for conversion of ___ to ___. phenylalanine to tyrosine
Phenylalanine hydroxylase or BH4 deficiency leads to accumulation of ___. phenyl ketones
Phenylalanine and tyrosine are degraded to ___ and ___. fumarate and acetoacetate
Fumarylacetoacetase deficiency leads to: Tyrosinemia I
Tyrosine aminotransferase deficiency leads to: Tyrosinemia II
p-hydroxyphenylpyruvate dioxygenase leads to: Tyrosinemia III
Tryptophan metabolism produces: glutaryl-CoA, alanine, acetyl-CoA, NAD precursors
Kynureninase is a ___ containing enzyme that is sensitive to ___ deficiency. PLP, B6
Created by: emyang on 2011-09-13



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