PRODUCTION OF BOVINE-PANCREATIC-TRYPSIN-INHIBITOR HOMOLOGS IN ESCHERICHIA-COLI AND THEIR CHARACTERIZATION

Biologically active bovine pancreatic trypsin inhibitor (BPTI) was pro duced in Escherichia coli using an OmpA leader-peptide fusion-protein system, and BPTI homologues were generated by cassette mutagenesis. Am ino acids in the reactive loop of alpha(1)-proteinase inhibitor (alpha (1)-PI) were incorporated into the reactive loop of BPTI in a stepwise approach such that the contribution of individual amino acids could b e assessed. The introduction of mutations into BPTI diminished the yie ld of heterologous protein relative to wild-type BPTI. However, for th ree BPTI homologues sufficient material was isolated to allow characte rization of the proteins by electrospray MS and N-terminal peptide seq uencing.