On the specific association of porcine erythrocyte catalase caused by formation of disulfide cross-links.

Porcine erythrocyte catalase (hydrogen-peroxide:hydrogen-peroxide oxidoreductase, EC 1.11.1.6) has been purified from porcine blood by DEAE-cellulose column chromatography, ammonium sulfate fractionation and CM-cellulose column chromatography. The purified enzyme was found to associate into larger molecules than the native one when it was stored at 4degrees C for more than one week. The associated molecules can be detected by gel filtration on a Bio-gel A-1.5 m column and disc gel electrophoresis as well as ultracentrifugal analysis. Molecular weights of the associated catalase molecules were about 500 000, 750 000, 1 000 000 and so forth estimated by gel filtration and disc gel electrophoresis, corresponding to dimer, trimer and tetramer respectively, of a native molecule (monomer) with a molecular weight of about 250 000. The association of catalase molecules is found to be time-dependent and to proceed seemingly from monomer through dimer as an intermediate. From the effects of several thiol reagents or reducing reagents on the association process and spectrophotometric titration of SH groups, it is inferred that this specific association of procine erythrocyte catalase is caused by formation of intermolecular disulfide cross-links due to air oxidation of SH groups in the protein moiety.