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Coenzymes and Vitamins

Coenzymes and Vitamins. C483 Spring 2013. 1. Unlike NADH and NADPH, FAD and FADH2 A ) donate one electron at a time. B ) donate one or two electrons at a time. C ) do not become positively charged. D ) A and C. E ) B and C.

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Coenzymes and Vitamins

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  1. Coenzymes and Vitamins C483 Spring 2013

  2. 1. Unlike NADH and NADPH, FAD and FADH2 A) donate one electron at a time. B) donate one or two electrons at a time. C) do not become positively charged. D) A and C. E) B and C. 2. Which coenzyme is likely involved in the reaction shown below? A) TPP. B) Biotin. C) Coenzyme A. D) FMN. 3. Pyridoxal phosphate is involved in which type of reaction? A) Oxidation of pyruvate. B) Production of new amino acids by transamination. C) Phosphate-transfer to produce ATP from ADP. D) methyl transfer

  3. 4. What kind of reaction is most important for the reactive center of lipoamide? A) Oxidation of a carbonyl group. B) Reduction of a disulfide bond. C) Formation of a Schiff base. D) Transamination THF is involved in transfer of carbon in what oxidation state? A) methyl B) methylene C) formyl D) carboxyl E) more than one of the above

  4. Terminology Vitamins and Minerals

  5. Vitamins Water and lipid solubility

  6. Objectives • Know selected structures (abbreviated structures) • Recognize types of reactions and relate to appropriate cofactor • Selected major mechanisms

  7. 1. Phosphorylation and Energy Transfer • ATP • Phosphate transfer • Hydrolysis • Reaction:

  8. 2. Redox Reactions • NADH/NAD+ (NADPH/NADP+) • Know abbreviated structure

  9. Reaction of NADH/NAD+ • 2 electron transfer • DH • cosubstrate • Know general oxidation and reduction Enzyme: Lactate DH

  10. Flavins • FAD/FADH2 • FMN/FMNH2 • Recognize abbreviated structure

  11. Reactions of Flavins • 1 or 2 electron transfer • Prosthetic group • No mechanisms

  12. 3. Acyl Carrier/Transfer • Coenzyme A • Pantothenate is vitamin B5 • Know abbreviated Acetyl CoA structure

  13. Reactions of Acetyl CoA • Thioester is a nucleophile • High energy linkage • Review Nucleophilic Acyl substitution • Reaction:

  14. Lipoamide • Technically, not a vitamin • Connected to protein—recognize abbreviated • Electrophilic acyl carrier—see mechanism • Redox reaction

  15. 4. Decarboxylation • Thiamine Pyrophosphate (TPP or TDP) • Know abbreviated structure

  16. Reactions • Decarboxylases • a-keto acids • Know initial phase of reaction:

  17. 5. Reactions of Amino Acids • Pyridoxal phosphate (B6) • Know abbreviated structure

  18. Schiff Base formation • Covalent imine formation with lysine • No mechanism—but structure of pdt • Bad mechanism given in book!

  19. Reactions • Decarboxylation, Racemization, Transamination, Others

  20. One Carbon Transfers • Recognize coenzyme • Know oxidation level of transfer

  21. SAM

  22. B-12

  23. THF

  24. Biotin

  25. Answers • E • A • B • B • E

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