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
Coenzyme
Carbon group
S-adenosyl methionine (SAM)
methyl
Cobalamine (B-12)
Methyl (and rearrangements)
Tetrahydrofolate (THF)
Methyl, methylene, formyl
Biotin
Carboxy

21. SAM

22. B-12

23. THF

25. Biotin

26. Answers E A B