Abstract:The protease isolated from Bacillus sp. BBE201108 was purified using ammonium sulfate fractional precipitation, dialysis, Q FF anion exchange chromatography and Superdex 75 gel filtration chromatograph after fermentation. A purified protease with a recovery of 6.48% had an overall purification of 10.55 fold and a specific enzyme activity of 2 575.45 U/mg. The molecular weight was approximately 46 000 as determined by SDS-PAGE. The α-subunit and α'-subunit of β-conglycinin could be effectively degraded after reaction with the soybean protein isolate (SPI) at pH 8.0 under 50 ℃ for 30 min. The protease was relatively stable over the pH range of 7.0-9.0 at 30~40 ℃. The protease activity enhanced by 5%in the presence of Ca2+, and inhibited by Mn2+, Fe2+ and Cu2+. A significant negative effect of phenylmethanesulfonyl fluoride (PMSF) was observed on the protease activity. The values of Km, Vmax, Kcat and Kcat /Km for the protease were 4.19 g/L, 4.04 g/ (L·s), 107.73 s-1 and 25.71 L/(g·s), respectively.
