Characterization of a strain producing cold-adapted protease and enzyme purification

A strain producing cold-adapted protease was isolated from soil and identified, named strain HL221. It was suggested that strain HL221 was the closest relative of Chryseobacterium scophthalmum, based on phylogenetic analysis of 16S rDNA with 99% of sequence identity, morphological, cultural and physiological characteristics of strain. The PAGE-homogenous protease was purified with 27 folds and recovery rate of 16% by (NH4)2SO4 fractionation, gel filtration on Sephadex G-75 and DEAE Sepharose Fast Flow. The molecular weight of the enzyme was determined to be 35000 Da by SDS-PAGE, its isoelectric point pI4.9 was determined by PAGE-IEF. The enzyme activity was optimal at pH7 with 25°C. The enzyme was stable over the range of pH 7-10 with below 25°C.