Exam 21: Amino Acid Metabolism

Enzyme A is involved in the metabolism of metabolite C to metabolite D.Enzyme A is part of a linear pathway involving ten enzymes ultimately converting B $\rarr$ F.High levels of F directly alter the activity of enzyme A and result in control over the overall pathway.Enzyme A

The majority of amino acids are deaminated by a ______ reaction.

The activity of bacterial glutamine synthetase is I.inhibited allosterically by tryptophan. II.inhibited allosterically by glucosamine-6-phosphate. III.activated by nine allosteric feedback inhibitors. IV.altered by covalent modification.

Ketogenic amino acids can be converted to I.glucose II.fatty acids III.ketone bodies IV.pyruvate

The synthesis of which of the following uses an aminotransferase in the first step of the synthesis?

The aminotransferase reaction, in which an enzyme-PLP Schiff base forms, I.is ATP dependent. II.results in formation of a hydroxylaldehyde. III.results in formation of an $\alpha$ -ketoacid. IV.requires an active site lysine.

Which of the following is TRUE regarding catabolism of leucine?

_____ catalyzes the synthesis of ____, a molecule that signals vasodilation, from the precursor _____

A number of compounds, including neurotransmitters, are synthesized from amino acids via decarboxylations.The enzymes catalyzing these steps usually use _______ as a cofactor.

Which of the following control the urea cycle? I.substrate concentration of the cycle enzymes II.allosteric activation of carbamoyl phosphate synthetase I III.concentration of glutamate IV.availability of glucose

Which of the following is required for synthesis of tryptophan?

Matching Choose the correct answer from the list. Not all the answers will be used. -Aminotransferases utilize a coenzyme synthesized from ______.

Proteins targeted for destruction via the ubiquitin pathway include I.proteins with a destabilizing N-end rule component. II.proteins with a PEST sequence. III.proteins that contain the RING finger E3 component named E3a. IV.protein with polyubiquitin proteins.

Heme biosynthesis

Oxidative deamination of glutamate I.generates NAD(P)H and $\alpha$ -ketoglutarate. II.is inhibited by glutamate. III.is activated by GTP. IV.eliminates the keto group from $\alpha$ -ketoacids.

The amino acids Ala, Cys, Gly, Ser, and Thr are all degraded to the metabolic intermediate ___ and are considered ____.

Which enzyme catalyses a reaction via an enzyme-bound adenylated intermediate?

Which of the following is TRUE about glutamine? I.It is formed from $\alpha$ -ketoglutarate. II.It donates an amino group to aspartate to form asparagine. III.It is directly required for ornithine synthesis. IV.It is a precursor to homoserine.

Which of the following statements about phenylalanine is(are)TRUE?

Which of the following glycolytic intermediates is the common precursor to serine, cysteine, and glycine?