Exam3-07answ - Name _ Section _ Net ID _ Exam III April 9,...

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Name _______________ Net ID ____________________ Section ______________ 1 Exam III April 9, 2007 Biochemistry 462b Write your name and UA NetID on all pages 1. _____ 2. _____ 3. _____ 4. _____ 5. _____ 6. _____ Total _____
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Name _______________ Net ID ____________________ Section ______________ 2 1. (8 pts total) The structural diversity of the compounds that are involved in feedback inhibition of glutamine synthetase is quite amazing. Write the names of 4 of these compounds. (2 pts) Answer: Any 4 of the 8 metabolites [see text, Figure 22-] that interact allosterically with glutamine synthetase. Other than glycine and alanine, they are diverse end-products of the many different pathways that originate from glutamate and/or glutamine. [CAP, Trp, His, Gly, Ala, AMP, CTP, glucosamine-6- P] Predict whether these compounds interact at a common regulatory site on the enzyme. Discuss the reasoning for your prediction. [i.e., Why you think that they would or would not interact at a common regulatory site?] (4 pts) Given the wide diversity of structures it is not plausible that they all have the same binding sites. If they all converged on one site, the excess of metabolite in one pathway could shut down all others and that is not likely to be a desirable outcome, since it would shut down the many metabolic systems that require and are therefore dependent on glutamine. 2. (8 pts) Gout can be caused either by: Defect A , that results in excess production of purines by de novo synthesis, or Defect B , that results from inability to properly excrete uric acid. Explain how, if a patient is fed 15 N-glycine, determining the amount of 15 N in excreted uric acid could be used to distinguish between these two forms of gout (i.e., what would be expected for defect A and for defect B). Assume that you have carried out control experiments with normal people and report the expected data relative to normals.
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Name _______________ Net ID ____________________ Section ______________ 3 Answer: In defect A , there should be much higher than normal amounts of
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This note was uploaded on 04/02/2008 for the course BIOC 462b taught by Professor Grimes,tsao,borque during the Spring '08 term at University of Arizona- Tucson.

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Exam3-07answ - Name _ Section _ Net ID _ Exam III April 9,...

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