Catalysis of a Biochemical Reaction At Physiological Temperatures. in Biologically Catalyzed Reactions the Reactants Are Known As Substrates and the Catalysts Are Naturally Occurring Macromolecular Substances Known As Enzymes. Enzymes Possess Specific Binding Sites For Substrates and Are Usually Composed Wholly or Largely of Protein But RNA That Has Catalytic Activity (ribozyme) Is Often Also Regarded As Enzymatic.
Catalysis of the Hydrolysis of Internal Alpha Peptide Bonds in a Polypeptide Chain by a Catalytic Mechanism That Involves a Catalytic Triad Consisting of a Serine Nucleophile That Is Activated by a Proton Relay Involving an Acidic Residue (e.g. Aspartate or Glutamate) and a Basic Residue (usually Histidine).