Ribonuclease of Bacillus intermedius 7 P. Purification by chromatography on phosphocellulose and several characteristics of the homogeneous enzyme]

A new procedure for isolation of homogenous ribonuclease of Bac. intermedius from a commercial source is described. The yields of 140 mg of RNAse from 200 g of the enzymic powder were attained. The amino acid composition of the enzyme was determined. The RNAse contains neither the sulfhydryl groups nor the disulfide bonds and has only one histidine residue. At the same time the amount of aromatic amino acid residues is relatively high. The enzyme is highly resistant to heat and acid treatment but is less stable in an alkaline solution. The pH optimum of the RNAse for the RNA digestion is 8,5; the temperature optimum for this reaction is 37 degrees. A spectrophotometric method for the RNAse activity assay using polyA as a specific substrate was developed. The purified product provides a suitable starting material for structural studies.