Activated human enzymes
Molecular enzymology - Enzymatic catalysis

Magnesium ions Mg ²⁺ are essential for the activity of kinases catalyzing phosphate group transfer. These enzymes are known as phosphotransferases. Under normal conditions, the Mg ²⁺ cation binds to ATP, and the kinases interact with the ATP coenzyme in the form ATP-Mg ²⁺ . This is an indirect activation.

Calcium cations Ca ²⁺ are activators of certain peptidases (peptide catabolism).

The chloride anions Cl ^– are activators of certain amylases (starch hydrolysis).