Biochemistry in Tables, Schemes, and Graphs - S.D. Zhamsaranova 2009

Enzymes
Coenzymes and Their Constituent Vitamins

Vitamin

Coenzyme form

Type of catalyzed reaction

Water-Soluble Vitamins

Thiamine (B1)

Thiamine pyrophosphate

Decarboxylation of a-keto acids

Riboflavin (B2)

Flavin mononucleotide, flavin adenine dinucleotide

Oxidation-reduction reactions

Nicotinic acid

Nicotinamide adenine dinucleotide, nicotinamide adenine dinucleotide phosphate

Oxidation-reduction reactions

Pantothenic acid

Coenzyme A

Acyl group transfer

Pyridoxine (B6)

Pyridoxal phosphate

Amino group transfer

Biotin

Biocytin

CO2 transfer

Folic acid

Tetrahydrofolate

One-carbon group transfer

Vitamin B12

Deoxyadenosylcobalamin

Transfer of a carbon-bonded hydrogen atom to the adjacent carbon atom

Ascorbic acid (C)

Unknown

Hydroxylation reactions

Fat-soluble vitamins

Vitamin A

Retinal

Visual process

Vitamin D

1,25-Dihydroxycholecalciferol

Regulation of Ca METABOLISM

Vitamin E

Unknown

Protection of Membrane Lipids

Vitamin K

Unknown

Decarboxylation reactions

Class="center">Coenzyme forms of RIBOFLAVIN

— flavin mononucleotide FMN (left) and flavin adenine dinucleotide FAD (right)

MECHANISM OF HYDROGEN ATOM TRANSFER BY FLAVIN Enzymes

NICOTINAMIDE (Vitamin PP) AND ITS COENZYME FORMS

MECHANISM OF HYDRIDE ION TRANSFER

One of the substrate hydrogen atoms is cleaved with two bonding electrons and transferred as a hydride ion (H) to the oxidized form of the coenzyme NAD+.

EXAMPLE OF ENZYMATIC OXIDATION

Enzymatic oxidation of malate to oxaloacetate by NAD-dependent malate dehydrogenase.



Last update: 06/08/2026

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