Some Physical Characteristics of a Proteinase from Aeromonas proteolytica

Abstract A proteinase has been isolated from culture filtrates of Aeromonas proteolytica essentially free of the aminopeptidase activity that is present in spent media from this organism. Sedimentation and moving boundary electrophoretic experiments indicated a high degree of homogeneity for the enzyme, which was isoelectric at approximately pH 3.5. The proteinase had a sedimentation coefficient of 3.50 S, a diffusion coefficient (d020,w) of 8.52 x 10-7 cm2 sec-1, and a partial specific volume, calculated from the amino acid composition, of 0.709 cm3 g-1. From both sedimentation velocity and sedimentation equilibrium, the molecular weight was 34,800; calculations of minimum molecular weight on the basis of zinc content yielded a value near 33,800 which indicated the presence of 1 g atom of zinc per mole of enzyme. Amino acid analysis revealed approximately 316 residues.