Enzymes, Coenzymes, and Cofactors

Biotin

Precursor: Biotin

Chemical Group Transferred: CO2

Coenzyme A

Precursor: Pantothenic acid

Chemical Group Transferred: acyl groups

Coenzyme B12

Precursor: Vitamine B12

Chemical Group Transferred: H atoms and alkyl groups

FAD

Precursor: Riboflavin (Vitamin B2)

Chemical Group Transferred: electrons with their H+’s

NAD

Precursor: Nicotinic acid acid (niacin)

Chemical Group Transferred: Hydride ions (2 electrons, and one H+)

Pyridoxal phosphate

Precursor: Amino groups

Chemical Group Transferred: Pyridoxine (B6)

Tetrahydrofolate

Precursor: Folate

Chemical Group Transferred: one-carbon groups

Thiamine pyrophosphate

Precursor: Thiamine (B1)

Chemical Group Transferred: aldehydes

Cu2+

Enzyme(s): Cytochrome oxidase

Fe2+/Fe3+

Enzyme(s): Cytochrome oxidase, Catalase, peroxidase, Fe-S proteins

Mg2+

Enzyme(s): Hexokinase, glucose-6-phophatase, pyruvate kinase

Ni2+

Enzyme(s): Urease

Se

Enzyme(s):Glyathione peroxidase

Zn2+

Enzyme(s): Carbonic anhydrase, alcohol dehydrogenase, carboxypeptidases A and B

Oxidoreductase

electron transfer between two molecules

Transferase

transfer of chemical groups (e.g. amino, phosphate, carboxyl) from one molecule to another

Hydrolase

transfer of functional groups to water, or cleavage using water

Lyase

addition of groups to C=C double bonds, or formation of C=C double bonds by removing groups

Isomerase

transfer of groups within a molecule to yield isomeric forms

Ligase

Use of ATP hydrolysis to form C-C, C-O, C-S, or C-N bonds