ZieglerLecture7-Enzymes2-Regulation-ppt1

ZieglerLecture7-Enzymes2-Regulation-ppt1 - Lecture 7:...

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Lecture 7: Lecture 7: Enzymes: Regulation and Enzymes: Regulation and Chemical Mechanisms Chemical Mechanisms BIOCHEMISTRY 100 Winter 2009 M. Ziegler
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Learning Objectives Learning Objectives 1. Terminology (explain/defne; understand use oF terms): allosteric, frst committed step, Feedback inhibition, cooperative substrate binding, eFFector, homotropic vs. heterotropic (eFFector), protein kinase, protein phosphatase, zymogen, active site, acyl group, catalytic triad oF serine proteases 2. Explain how you would predict what step in a metabolic pathway would be the regulated step For that pathway. 3. Sketch plots oF V o vs. [S] For an allosteric enzyme that illustrate positive homotropic regulation and positive and negative heterotropic regulation, with ATCase as an example. In other words, sketch (all on the same axes) V o vs. [Asp] curves with no heterotropic regulators present, with an allosteric inhibitor, and with an allosteric activator. 4. Explain the rationale For why the step catalyzed by ATCase is the regulated step in the pyrimidine biosynthetic pathway, why ATCase is inhibited by CTP, and why it is activated by ATP. 5. Write the reactants and products For general reactions catalyzed by kinases and by phosphatases , and by protein kinases and phosphoprotein phosphatases. 6. Explain how phosphorylation/dephosphorylation oF an enzyme might change its activity From less active to more active and vice versa. 7. Name the kinds oF amino acid residues in enzymes that can be modifed
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Learning Objectives, continued Learning Objectives, continued 7. (continued) by phosphorylation/dephosphorylation. 8. Explain in general terms (no specifc cleavage sites) how chymotrypsinogen is activated to produce chymotrypsin. In general terms, explain how a cleavage event is “translated” into an activity change. 9. List 7 general kinds oF catalytic mechanisms used by enzymes, and brie±y explain general acid-base catalysis and nucleophilic catalysis. 10. ²or proteolysis (hydrolysis oF a peptide bond by a protease like chymotrypsin), what group needs to be made more susceptible to nucleophilic attack than it would be in the uncatalyzed reaction? 11. In brieF general terms, what is the main diFFerence between uncatalyzed peptide hydrolysis and chymotrypsin-catalyzed peptide hydrolysis. 12. In the reaction catalyzed by serine proteases like chymotrypsin, what is the nucleophile in the reaction? What mechanism is used by what other Functional group in chymotrypsin to make that nucleophile more reactive? Brie±y, what are the roles oF the 3 members oF the catalytic triad? 13. What is the covalent intermediate in the chymotrypsin-catalyzed reaction called, and what kind oF covalent bond attaches it to the enzyme? 14. Why do some enzymes need coenzymes ? 15. Recognize the structure oF NAD + /NADH. What does this coenzyme carry (transFer From one compound to another), and what position on the NAD(H) structure is the “business” position For the carrying?
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Enzyme Regulation Enzyme Regulation Amounts of many key enzymes are regulated at the level of
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This note was uploaded on 02/25/2009 for the course BCH 100 taught by Professor Staff during the Spring '08 term at UC Riverside.

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ZieglerLecture7-Enzymes2-Regulation-ppt1 - Lecture 7:...

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