Cofactor
A non-protein chemical component required for an enzyme to function.
Unit
Dimensionless
In depth
Cofactors may be inorganic metal ions or organic coenzymes, and they may be loosely bound or permanently attached as prosthetic groups. Metal ions typically stabilise negative charge in the transition state or participate directly in redox chemistry.
Examples in the real world
Zinc in carbonic anhydrase, magnesium in every kinase, and iron within the haem of cytochromes.