Partial purification of cysteine sulfinic acid decarboxylase from calf brain

Cysteine sulfinic acid decarboxylase (EC 4.1.1.29) was purified from calf brain by pH precipitation, ammonium sulfate fractionation, gel filtration and DEAE-Sephadex A-50 chromatography. The enzyme preparation decarboxylated both cysteine sulfinic acid and cysteic acid at all steps of the purification and the ratio of the velocity of decarboxylation of cysteine sulfinic acid to that of cysteic acid was constant, about 2, throughout the purification procedure. The pH optimum was 7.2 both for cysteine sulfinic acid and cysteic acid. The molecular weight of the enzyme was estimated at 65 000 using gel filtration on a Sephadex G-200 column. Its Km's were 0.9 mM for cysteine sulfinic acid and 1.6 mM for cysteic acid, with Vmax values of 60.5 and 33.5 nmol/h(mg protein), respectively.