Subunit III of ruminant procarboxypeptidase A-S6 complexes and pancreatic proteases E. A new family of pancreatic serine endopeptidases? |
| |
Authors: | C Cambillau B Kerfelec M Sciaky C Chapus |
| |
Institution: | Groupe de Cristallographie des Protéines, CRMC2-CNRS, Marseille, France. |
| |
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. |
| |
Keywords: | |
|
|