Rat liver cysteine sulfinate decarboxylase: Some observations about substrate specificity

The procedures in use for the determination of the activity of cysteine sulfinate decarboxylase (l-cysteine sulfinate carboxy-lyase, EC 4.1.1.29) in rat liver homogenate were evaluated. In addition, since we observed that decarboxylation of cysteine sulfinate as well as of cysteate occurred throughout the different purification steps of the enzyme, our results support the hypothesis that a single enzyme is responsible for both decarboxylations. The molecular weight of the enzyme was estimated at 65 000–70 000, using a column of Sephadex G-100 and at 78 000–85 000 using a Biogel P-15o column. A reason for this discrepancy is suggested.