Purification, Crystallization and Some Enzymatic Properties of Acid Protease of Cladosporium sp. No. 45-2

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An acid protease of Cladosporium sp. No. 45-2 was purified and crystallized by precipitation with ammonium sulfate, fractional precipitation with acetone, and pH adjustment. About 600mg of third crystallized preparation was obtained from one liter of culture broth. The purified enzyme was chromatographically homogeneous and confirmed to be monodispersive by physicochemical criteria such as ultracentrifugal and electrophoretical analysis. The enzyme was most active at pH values between 2.5 and 2.7 toward both casein and hemoglobin and was stable at pH values from 2.5 to 7.0 on twenty hour incubation at 30°C.
Millimolar concentration of sodium lauryl sulfate markedly inhibited the enzyme, vv heares diisopropyl phosphorofluoridate, sulfhydryl reagents, ethylenediaminetetra acetic acid, and divalent metal ion relatively little affected the activity. The enzyme was most resistant toward S-PI among the acid proteases tested.