| Abstract
| - Bacillus amyloliquefaciens FSE-68 isolated from meju, a Korean soybean fermentation starter, wasidentified on the basis of biophysical tests and 16S rRNA gene sequence. A neutral metalloprotease(NPR68) and an alkaline serine-protease (APR68) were purified by ammonium sulfate precipitationand cation exchange chromatography and identified on the basis of their activities at different pHvalues and the selective protease inhibitors. The molecular weights of NPR68 and APR68 measuredwith ESI-MS were 32743 (± 0.8) and 27443 (± 0.5) Da, respectively. Against oxidized insulin chains,the NPR68 has a cleavage preference at the site where leucine is located as a P1‘ residue followedby phenylalanine, and the APR68 has broad specificity and favors leucine at the P1 site. Theseresults indicate that the proteases are natural variants of subtilisin and bacillolysin. Keywords: Bacillus amyloliquefaciens; strain identification; protease; specificity; insulin; purification;meju
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