There are so many of these, but enzymes are known to catalyze about 4,000 biochemical reactions.
Enzymes are usually named according to the reaction they carry out. Typically, to generate the name of an enzyme, the suffix -ase is added to the name of its substrate (e.g., lactase is the enzyme that cleaves lactose) or the type of reaction (e.g., DNA polymerase forms DNA polymers) or sucrase cleaves sucrose, maltase cleaves maltose, protease cleaves proteins.