MILK-CLOTTING ENZYME FROM MICROORGANISMS .6. PROPERTIES OF CRYSTALLINE MILK-CLOTTING ENZYME (MUCOR RENNIN) ISOLATED FROM MUCOR PUSILLUS VAR LINDT

The crystalline milk-clotting enzyme isolated from Mucor pusillus var. Lindt, has an acid protease activity. The optimum pH for the digestion of κ-casein is 4.5, while that for hemoglobin digestion is 4.0. The physical properties of the crystalline enzyme are as follows: partial specific volume is 0.74; sedimentation coefficient is 2.39·10-13 (cm·g·sec-1·dyne-1); diffusion coefficient, 7.9·10-7 cm2·sec-1; frictional coefficient ( f f0), 1.33. Molecular weight was given as 29 000 by Svedverg's method and 30 600 by Yphantis' method. The number of amino acid residues contained in 1 mole of protein of the crystalline enzyme is 277-281 ((Cys)2, Met3, Asp44, Thr21, Ser22, Glu20, Pro14, Gly34, Ala16-17, Val24, Ile12, Leu15, Tyr13, Phe19, His1-2, Lys11-12, Arg4, Trp2-3). © 1969.