, Volume 7, Issue 4, pp 335-337

First online:

Cold-active serine alkaline protease from the psychrophilic bacterium Pseudomonas strain DY-A: enzyme purification and characterization

  • Runying ZengAffiliated withThird Institute of Oceanography, State Oceanic AdministrationSchool of Life Sciences, Xiamen University Email author 
  • , Rui ZhangAffiliated withThird Institute of Oceanography, State Oceanic Administration
  • , Jing ZhaoAffiliated withSchool of Life Sciences, Xiamen University
  • , Nianwei LinAffiliated withSchool of Life Sciences, Xiamen University

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An extracellular protease was purified from a deep-sea psychrophilic bacterium strain DY-A which was identified as a Pseudomonas species. The optimal growth and protease-producing temperatures of the strain were all 10°C, and the protease was secreted only at temperatures under 20°C. The enzyme was most active at 40°C and at pH 10.0. It was inhibited by phenylmethyl sulfonylfluoride and diisopropyl fluorophosphate, indicating that it is a serine protease. Chelators such as EDTA, EGTA, 1,10-phenanthroline and 2,2′-bipyridyl produced a decrease of activity. The enzyme was sensitive to denaturing agents such as SDS, urea, and guanidine HCl and resistant to thiol-containing reducing agents such as dithiotreitol. The enzyme was active towards N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide and N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide. The native molecular mass of the enzyme determined by native PAGE and SDS-PAGE was 25 kDa.


Deep sea Psychrophile Serine protease