Purification and Characterization of a Subtilisin D5, a Fibrinolytic Enzyme of Bacillus amyloliquefaciens DJ-5 Isolated from Doenjang

Purification and Characterization of a Subtilisin D5, a Fibrinolytic Enzyme of Bacillus amyloliquefaciens DJ-5 Isolated from Doenjang

The fibrinolytic enzyme, subtilisin D5, was purified from the culture supernatant of the isolated Bacillus amyloliquefaciens DJ-5. The molecular weight of subtilisin D5 was estimated to be 30 kDa. Subtilisin D5 was optimally active at pH 10.0 and $45^{\circ}C$. Subtilisin D5 had high degrading activity for the A$\alpha$-chain of human fibrinogen and hydrolyzed the $B{\beta}$-chain slowly, but did not affect the $\gamma$-chain, indicating that it is an $\alpha$-fibrinogenase. Subtilisin D5 was completely inhibited by phenylmethylsulfonyl fluoride, indicating that it belongs to the serine protease. The specific activity (F/C, fibrinolytic/caseinolytic activity) of subtilisin D5 was 2.37 and 3.52 times higher than those of subtilisin BPN' and Carlsberg, respectively. Subtilisin D5 exhibited high specificity for Meo-Suc-Arg-Pro-Tyr-pNA (S-2586), a synthetic chromogenic substrate for chymotrypsin. The first 15 amino acid residues of the N-terminal sequence of subtilisin D5 are AQSVPYGISQIKAPA; this sequence is identical to that of subtilisin NAT and subtilisin E.