1. Cofactors and Coenzymes
Title slide - this section. Cofactors ( an atom or molecule essential for the action of a large molecule, cofactors may include metals or coenzyme) and coenzymes - an organic substances that enhances or is necessary for the action of enzymes.

2. Cofactors
Groups or molecules (other than amino acid residues) which are important to catalysis
Metals
Coenzymes
If tightly bound, it is called a prosthetic group
Enzyme without prosthetic group (cofactor)
Apoenzyme
Enzyme with prosthetic group (cofactor)
Holoenzyme
Definitions illustrated.

3. Catalysis by Coenzymes
Some common coenzymes Transfers
Oxidation/Reduction
Nicotinamide Adenine Dinucleotide (NAD+)
Flavin Adenine Dinucleotide (FAD)
Hydride ion (H-)
Electrons
Redox coenzymes.

4. Catalysis by Coenzymes
Some common coenzymes
One carbon metabolism
Biotin
Tetrahydrofolate
Transfers
CO2
One carbon groups
Single carbon functional coenzymes.

5. Catalysis by Coenzymes
Some common coenzymes
Acyl groups and others
Coenzyme A
Lipoic acid
Thiamine pyrophosphate
Pyridoxal phosphate
5’-Deoxyadenosyl-cobalamin
Transfers
Acyl groups
Aldehydes
Amino groups and amines
Alkyl groups
Coenzymes involved in group transfers.

6. Vitamin Derived Coenzymes
Symptoms of vitamin deficiencies

7. Vitamin Derived Coenzymes
Symptoms of vitamin deficiencies.

8. Examples of Coenzyme Catalysis
Uncatalyzed reaction
Decarboxylation of an amino acid in an uncatalyzed reaction.

9. Examples of Coenzyme Catalysis
Catalysis with pyridoxal phosphate (Vitamin B6 derivative)
The amino acid adds to pyridoxal phosphate to form a Schiff base which is a key intermediate in many transformations.
Schiff Base

10. Examples of Coenzyme Catalysis
Electron shifts occur and carbon dioxide is lost.

11. Examples of Coenzyme Catalysis
The amine is released from the coenzyme following more electron shifts.

12. Examples of Coenzyme Catalysis
Nicotinamide adenine dinucleotide and alcohol dehydrogenase
NAD+ is reduced producing NADH and in the next slide this reduced form of the coenzyme is used to produce ethyl alcohol.
NADH
NAD+

13. Examples of Coenzyme Catalysis
Reduction of acetaldelhyde to ethyl alcohol by alcohol dehydrogenase using NADH and H+. . Zn 2+ is a cofactor.

14. NAD+ reactive site, the yellow R is an H in NAD+ and a phosphate in NADP+

15. FAD reactive sites

16. Oxidation of an alcohol to a ketone or aldelhyde

17. FAD oxidation of a hydrocarbon chain - this kind of reaction occurs in fatty acid oxidation

18. The oxidized and reduced forms of FAD

19. Complete reduction of a keto to a CH2

20. CoA (coenzyme A) is an acyl carrier. The Ac~CoA bond is high energy.

21. The reactive site on CoA is the -SH

22. Lipoamide also carrier a H

23. Think chemistry

24. Oxidation examples from the Krebs citric acid cycle

25. ATP is carrying phosporyl groups. Other carrying coenzymes.

26. Close up of ATP - base in blue, ribose in red, two phosphate in yellow and one in grey.

27. NADH contains an adenyl group from ATP.

28. The coenzyme form contains an adenyl group.

29. CoA also contains an adenyl group with an extra phosphate