Hydrolases;
Acting on peptide bonds (peptidases);
Serine endopeptidases
Reaction(IUBMB)
Cleavage after basic amino-acid residues, with Arg strongly preferred to Lys
Comment
This type-II membrane-associated serine peptidase has been implicated in cell growth and development [1,3]. The enzyme has been shown to activate blood coagulation factor VII by cleavage of the Arg152!Ile153 peptide bound in BHK cells, thus indicating a possible role in the initiation of blood coagulation [2]. There is no cleavage after aromatic or aliphatic residues [1]. The occupancy of the S2 site is an absolute requirement for catalysis and a basic residue at that site is preferred to an aliphatic residue. The nature of the residue at S3 also affects hydrolysis, with Gln being much more favourable than Ala [1]. Belongs in peptidase family S1A.
Hepsin, a putative membrane-associated serine protease, activates human factor VII and initiates a pathway of blood coagulation on the cell surface leading to thrombin formation.
