Serine hydrolase
Serine hydrolases are one of the largest known enzyme classes comprising approximately ~200 enzymes or 1% of the genes in the human proteome. A defining characteristic of these enzymes is the presence of a nucleophilic serine in their active site, which is used for the hydrolysis of substrates. Catalysis proceeds by the formation of an acyl-enzyme intermediate through this serine, followed by water/hydroxide-induced saponification of the intermediate and regeneration of the enzyme. Unlike other non-catalytic serines, the nucleophilic serine of these hydrolases is typically activated by a proton relay involving a catalytic triad consisting of the serine, an acidic residue (e.g. aspartate or glutamate) and a basic residue (usually histidine), although variations on this mechanism exist.

Superfamilies of serine hydrolases includes:

  Serine proteases, including trypsin, chymotrypsin, and subtilisin
  Extracellular lipases, including pancreatic lipase, hepatic lipase, gastric lipase, endothelial lipase, and lipoprotein lipase
  Intracellular lipases, including hormone sensitive lipase, monoacylglycerol lipase, adipose triglyceride lipase, and diacylglycerol lipase
  Cholinesterases, including acetylcholinesterase and butyrylcholinesterase
  Small molecule thioesterases, including fatty acid synthase and the acyl-CoA thioesterases
  Some phospholipases, including phospholipase A2 and platelet activating factor acetylhydrolase
  Protein and glycan hydrolases, including protein phosphate methylesterase 1, acyloxyacyl hydrolase and sialic acid acetylesterase
  Some amidases, including fatty acid amide hydrolase
  Some peptidases, including dipeptidyl peptidase 4, fibroblast activation protein, and prolylendopeptidase

See also 
 Activity based proteomics
 Alpha/beta hydrolase fold
 Amide
 Enzyme
 Ester
 List of enzymes
 Thioester

References

Hydrolases
EC 3.1