2015 Volume 21 Issue 5 Pages 739-744
Protease from lactic acid bacteria is of great importance to flavor and texture quality of fermented foods. An acidic protease from Pediococcus pentosaceus 220 was purified to homogeneity with a 11.5-fold increase in specific activity and 13.4% of recovery by precipitation with ammonium sulfate (20 – 60%, w/v), DEAE-Sepharose CL-6B ionic exchange chromatography, and Sephadex G-75 gel filtration chromatography. The molecular weight of the purified protease was estimated to be 37 kDa by Sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The optimum pH and temperature for protease activities were around pH4.0 and 35°C, respectively. The enzyme was stable at 20 – 40°C and showed pH stability between 4.0 and 7.0. The protease was activated by Ca2+, but inhibited by Zn2+, Mg2+ and Fe3+. The enzyme activity was also strongly inhibited by Sodium dodecyl sulfate and EDTA. It could be deduced that the purified enzyme was an acidic metalloprotease.