Extracellular proteolytic enzymes of psychrophilic bacteria. I. Purification and some properties of enzymes of an obligately psychrophilic red-pigmented bacterium

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Abstract
Proteinase in culture fluids of an obligately psychrophilic bacterium was precipitated by ammonium sulfate and fractionated by gel filtration and DEAE-cellulose chromatography. Three purified fractions (I-1, I-2, and III-1) with proteinase activity were obtained. On the basis of reactions and characteristics (i.e. effect of pH, heat, and metal ions on activity and stability, hydrolysis of synthetic peptides and of natural proteins) fractions I-1 and III-1 appeared to be very similar whereas fraction I-2 was different. When proteinase preparations were examined by electrophoresis, fractions I-1 and III-1 gave similar patterns; fraction I-2 gave a different one. From the results it is suggested that the organism produces two proteinases and that possibly fraction I-1 represents an aggregation of molecules of III-1 and that fraction I-2 is a different proteinase.