Crystallization and Alkali-Denaturation of Porcine Blood Catalase

Abstract

A procedure was devised for obtaining porcine blood catalase in a pure crystalline state. A relatively high yield of 180 mg. pure crystalline product was obtained from 2,600 ml. of red corpuscles (about 5 liter blood). Pure porcine blood catalase is characterized by a Kat-f value of 61,500± 2,500 and contains no blue substance as prosthetic group. The molecular weight and frictional ratio were determined to be 243,000 and 1.24, respectively. On alkali-treatment at pH 12.0, the molecule of porcine blood catalase was found to split into homogeneous subunits with a molecular weight 83,000 one-third that of the original protein. The frictional ratio of the subunit was found to be 2.20. On the basis of this finding it is inferred that the molecule of porcine blood catalase consists of three equally sized subunits. The absorption spectrum of the alkali denatured catalase was found to be markedly different from that of the native catalase. No enzymatic activity was found in this state of denaturation.