An enzymatic and immunological comparison of two proteases from a transformable Bacillus subtilis with the “subtilisins”

Abstract

Two extracellular endopeptidases isolated from a transformable strain of Bacillus subtilis have been compared with the extensively studied subtilisins Carlsberg and Novo (or Nagarse). The rales of hydrolysis of dimethylated casein, dimethylated protamine, hide powder, and two amino acid esters have been measured for each of these enzymes. One of the new enzymes shows hydrolysis kinetics very similar to those observed for subtilisins Novo and Nagarse, while the other enzyme has esterolytic rates up to 200 times greater than those observed for the subtilisins. Characterization of the digestion products produced by the action of each of the enzymes on casein revealed that the enzyme most similar to the Novo or Nagarse enzyme in kinetic properties was also similar in the specificity of peptide linkages cleaved, while the enzyme with high esterolytic activity yielded a high level of free amino acids in the casein hydrolyzates. The first enzyme has immunological cross-reacting properties similar, but not identical, to those of subtilisins Novo or Nagarse. The second enzyme was not observed to cross-react immunologically with any of the others. On the basis of the kinetic and immunological data, it is concluded that, although one of the new proteases is similar to the Nagarse or Novo enzyme, both of these new enzymes should be considered molecular entities distinct from the subtilisins.