Exam 18: Nucleotide Metabolism

Which of the following is a coenzyme that is derived from ATP?

An in vitro experiment with all precursors available for the conversion of dUMP to dTMP would also need to include thymidylate synthase and two additional enzymes necessary for the regeneration of N⁵,N^{1 0}-methylenetetrahydrofolate. What are the two enzymes?

An enzyme panel analysis of a patient reveals a lack of , which is an indication of Lesch-Nyhan syndrome.

To purify glutathione reductase to carry out a kinetics analysis, which organism would be the best source of the enzyme?

To study the allosteric regulation of E. coli ribonucleotide reductase in a cell-free in vitro system, which of the following would be a good choice to add to the system?

What is the name of the compound below, which is an intermediate in the breakdown of some pyrimidines?

During the biosynthesis of UMP from carbamoyl phosphate and aspartate, dihydroorotate is converted to which of the following compounds?

The activity site of ribonucleotide reductase can bind two different molecules, whereas the specificity site can bind several. Construct a situation where the activity of the enzyme is inhibited by choosing the identity of the molecules bound to each site.

Place the following steps in their proper order starting with dUMP and N⁵,N^{1 0}-methylenetetrahydrofolate as substrates. 1. Formation of tetrahydrofolate 2) Formation of N⁵,N^{1 0}-methylenetetrahydrofolate 3) Formation of 7,8-dihydrofolate

If GMP radiolabeled at the nitrogen atom indicated by the * were metabolized to uric acid, which of the following molecules along the pathway would also be radioactive?

When analyzing the production of dTMP by thymidylate synthase in a cell-free system, which of the following compounds would be found as an additional product of this enzyme?

Which of the following is an intermediate in the conversion of AMP to uric acid but NOT an intermediate in the conversion of GMP to uric acid?

Which of the following is the precursor of the indicated carbon atom in a pyrimidine ring?

To synthesize nucleotide monophosphates from oligonucleotides in a test tube, which enzyme must be included in the reaction mixture?

A mutation in may alter the rate at which UT is converted to CTP.

Samples from a bird, reptile, amphibian, and primate were analyzed by Western blotting for the expression of allantoinase, the enzyme that converts allantoin to allantoic acid. Unfortunately the researcher forgot the order that the samples were loaded into the gel. Luckily, only a single sample indicated allantoinase. Which sample contained allantoinase?

Describe how feedback inhibition by GDP may affect the flux of the ATP synthesis pathway.

Tyr122 is important in the mechanism of the E. coli ribonucleotide reductase. The function of this amino acid in the mechanism is to

Contrast the role of kinases and nucleotidases in the nucleotide salvage pathway.