Purification and characterization of rhodanese from Acinetobacter calcoaceticus

Rhodanese (thiosulfate : cyanide sulfur transferase, EC 2,8,1,1) was found to be contitutively present as an intracellular enzyme in Acinetobacter calcoaceticus. The soluble enzyme was purified 40.9-fold by a procedure which included ultracentrifugation, ethanol precipitation, CM-Sephadex batchwise separation, QAE-50 ion exchange chromatography, and socrose density gradient ultracentrifugation. The enxyme had a molecular weight of approximately 35000 with a pH optimum of 8-8.5. Activity was substantially enhanced by supplements of 2-mercaptoethanol and to a lesser extent by cysteine-HCl or reduced gluthatione. No degradation of the enzyme into smaller subunits was observed when treated with 2-mercaptoethanol.