Purification and characterization of a new peptidase, bacillopeptidase DJ-2, having fibrinolytic activity: produced by Bacillus sp. DJ-2 from Doen-Jang

Abstract

A new Bacillus peptidase, bacillopeptidase DJ-2 (bpDJ-2), with molecular mass of 42 kDa and isoelectric point (pI) of 3.5-3.7, was purified to homogeneity from Bacillus sp. DJ-2 isolated from Doen-Jang, a traditional Korean soybean fermented food. The enzyme was identified as an extracellular serine fibrinolyfic protease. The optimal conditions for the reaction were pH 9.0 and 60°C. The first 18 amino acid residues of the N-terminal amino acid sequence of bpDJ-2 were TDGVEWNVDQIDAPKAW, which is identical to that of bacillopeptidase F (bpf). However, based on their N-terminal amino acid sequence, molecular size, and pI, it is different from that of bpf and extracellular 90 kDa. The whole (2,541 bp, full-bpDJ-2) and mature (1,956 bp, mature-bpDJ-2) genes were cloned, and its nucleotide sequence and deduced amino acid sequence were determined. The expressed proteins, full-bpDJ-2 and mature-bpDJ-2, were detected on SDSPAGE at expected sizes of 92 and 68 kDa, respectively.