Protease S.aureus V8 (endoproteinase-glu-C) specifically cleaves peptide bonds on the COOH-terminal side of either aspartic or glutamic acids. In the presence of ammonium, the enzyme specificity is limited to glutamic sites. It has a molecular weight of 27000 daltons and optimum pH's of 4,0 and 7,8 with hemoglobin as the substrate. Enzyme activity is determined by the casein digestion assay.