Pure milk-clotting protease (MCP-76) is isolated by isotachophoresis at pH 5.0. The native molecule has only one protein chain. It is a metaloenzyme containing zinc. The pure MCP-76 has a molecular weight of 33 000 (+/- 1500) and by diphenyl-indenonyl-isothiocyanate method showed arginine as N-terminal amino acid.