Characterization and application of a novel halotolerant protease with no collagenase activity for cleaner dehairing of goatskin

Abstract

The current study focused on the substitution of toxic Na2S with bio-enzyme G3726, a novel serine protease heterologously expressed by Bacillus subtilis strain SCK6. This protease was purified to electrophoretic homogeneity with 39.43 % recovery, 7.03-fold purification and an estimated molecular mass of 36 kDa. The maximal activity was achieved at pH 8, 75 °C and 40 g L−1 NaCl, and more than 70 % of the activity was retained across the broad salinity range of 0–200 g L−1. G3726 was activated by Sr2+ and Ca2+, displayed considerable stability to benzene and ethanediol, and exhibited excellent compatibility with Tweens (20 and 80) and Triton X-100. Simultaneously, the 3D structure of G3726 was constructed by homology modeling, and interacted well with the cementing substances glycoprotein and proteoglycan in the hair pores. Moreover, G3726 showed no collagenase activity, and could thoroughly dehair goatskin within 4 h without any damage, which was better than industrial enzyme AS1.398 and chemical Na2S. As compared to Na2S, G3726 enzymatic dehairing showed reduction in BOD5, COD and TSS by 53.81, 52.78 and 65.52 %, respectively, endowing the leather better physical properties. These outstanding findings indicate that protease G3726 may have application in dehairing for environment-friendly leather processing.