Co-factor

A co-factor (or cofactor) is a chemical compound which is not a protein, but is attached to a protein. The compound is needed for the protein's biological activity. In most cases, the protein will be an enzyme, and the cofactor will help the enzyme work. If so, the cofactors are also called coenzymes.^[1] ^[2]

Cofactors which are complex organic molecules are often called coenzymes. If connected by a covalent bond they are a prosthetic group. But if they are just temporarily connected then the cofactor is a cosubstrate.

Some enzymes need several cofactors. Organic cofactors are often vitamins, or made from vitamins. Metallic ions are often cofactors, but many cofactors have both inorganic and organic parts.

Ion	Examples of enzymes containing this ion
Cupric	Cytochrome oxidase
Ferrous or Ferric	Catalase Cytochrome (via Heme) Nitrogenase Hydrogenase
Magnesium	Glucose 6-phosphatase Hexokinase DNA polymerase
Manganese	Arginase
Molybdenum	Nitrate reductase Nitrogenase
Nickel	Urease
Zinc	Alcohol dehydrogenase Carbonic anhydrase DNA polymerase

A simple [Fe₂S₂] cluster containing two iron atoms and two sulfur atoms, coordinated by four protein cysteine residues

References

↑ Abercrombie M. et al 1990. The Penguin dictionary of biology. London: Penguin, p126.
↑ "coenzymes and cofactors". academic.brooklyn.cuny.edu. Retrieved 2018-01-15.

[1] Abercrombie M. et al 1990. The Penguin dictionary of biology. London: Penguin, p126.

[2] "coenzymes and cofactors". academic.brooklyn.cuny.edu. Retrieved 2018-01-15.

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v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)