Crystalline Milk-Clotting Protease from Mucor Miehei and Some of its Properties

A milk--clotting protesse has been separated in crystalline form from filtrates of Mucor michel.It is the major proteolytic component produced by the microorganism, and has a molecular weight of 34,000 to 39,000.Determination of amino acid composition indicates: Asp4~, Thrls, Set25, Glu15, Ala2e, ¥a11~, l~(Cys)4, Mets, Ileu11, LeUl4, Tyr13, Phen14, Ornl, Lyss, His2, Arg4, Trya (NH3)39.The pH optima for proteolysis of hemoglobin, casein and bovine serum albumin classify the enzyme as an acid protease.The enzyme is most stable at acid pH.The effects of inhibitors indicate that this clotting enzyme is not metal dependent and does not have serine or SIt active groups.Aluminum sulfate has a peculiar depressing action on clotting activity, and study of the mechanism has pointed out similarities between this M. miehei enzyme and calf rennin.