Studies on proteolytic activity in commercial myoglobin preparations.

Commercial myoglobin preparations from horse skeletal muscle degraded casein. The maximum activity was at pH8-8.5. A muscle myofibril preparation was also attacked. The protease could be partly separated from the myoglobin by selective ultrafiltration through a membrane with an exclusion limit of mol.wt. 30000. A greater than 1000-fold purification of the proteolytic activity was achieved by affinity chromatography with soya-bean trypsin inhibitor bound to CM-cellulose. The enzyme preparation hydrolysed p-toluenesulphonyl-l-arginine methyl ester and N-benzyloxycarbonyl-l-tyrosine p-nitrophenyl ester. Its activity was inhibited strongly by soya-bean and ovomucoid trypsin inhibitors, serum and the soluble fraction of muscle homogenates. EDTA, p-chloromercuribenzoate and phenylmethylsulphonyl fluoride also caused some inhibition.