title: Subunit III of ruminant procarboxypeptidase A-S6 complexes and pancreatic proteases E. A new family of pancreatic serine endopeptidases?
abstract: Subunit III (BSIII) of the bovine ternary complex of procarboxypeptidase A-S6 (PCPA-S6), a defective serine endopeptidase-like protein, actively synthesized by the pancreas of some ruminant species, is highly homologous to human protease E (HPE). Both proteins possess the same atypical disulfide bridge in position 98-99b. They are structurally related to porcine elastase 1 and human elastase 2 (about 56% identity). However, in contrast to those two enzymes which have an overall positive net charge, BSIII and HPE are negatively charged. Three-dimensional models of BSIII and HPE have been constructed from the crystallographic structure of porcine pancreatic elastase 1. The inhibitor-binding site for TFAI in these three proteins seems to be very similar; the atypical disulfide bridge does not seem to be involved in this binding site. The specific structural features of BSIII and HPE strongly support the assumption that BSIII is a truncated protease E and that both proteins belong to a separate serine endopeptidase family.
authors.affiliation: Groupe de Cristallographie des Protéines, CRMC2-CNRS, Marseille, France.
authors.forename: C
authors.initials: C
authors.lastname: Cambillau
authors.forename: B
authors.initials: B
authors.lastname: Kerfelec
authors.forename: M
authors.initials: M
authors.lastname: Sciaky
authors.forename: C
authors.initials: C
authors.lastname: Chapus
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003461:Crystallography; D004220:Disulfides; D004563:Electrochemistry; D004792:Enzyme Precursors; D006801:Humans; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes; D010179:Pancreas / Q000201:enzymology*; D011487:Protein Conformation; D012689:Sequence Homology, Nucleic Acid; D012697:Serine Endopeptidases; D013552:Swine
chemical_list: D004220:Disulfides; D004792:Enzyme Precursors; D009097:Multienzyme Complexes; C055863:procarboxypeptidase A-S6; C055862:BSIII; D012697:Serine Endopeptidases; C028734:protease E