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  Protease activity of the cultures was screened from 260 strains of Antarctic bacteria taken from sea ice, and strain NJ341 showed the highest protease activity (176 U ml-1). Strain NJ341 was identified as the genus Colwellia from its biochemical characteristics and 16S rDNA sequence. Phylogenetic tree analysis by neighbor -joining method also exhibited that strain NJ341 was more closely related to the genus Colwellia (levels of similarity, 89.8 to 94. 8% ), and its closest relative wasC. piezophila , named as Colwellia sp. NJ341. The purified protease had an apparent Mr 60 kDa by SDS - PAGE and MALDI -TOF MS. It was active over a wide range of pH (5.0-12.0), and the optimum protease activity was at around 35℃ and its activity under 0℃ exhibited nearly 30% of the maximum activity. And the protease activity retained about 50% of its maximum activity for 50 min at 40℃. In addition, the protease was also completely inhibited by Fe2+ , but not or only partially inhibited by other inhibitors and metal ions. The maximum kcat/Km value was observed at 30℃, and the activation energy for cold - active protease was 35. 5 kJmor-1. It was completely inhibited by PMSF, which indicated that it was a cold - active serine protease. The present protease is the first cold - active serine protease found in Colwellia species.……   
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