Properties of Azotobacter vinelandii rhodanese

Rhodanese (thiosulfate: cyanide sulfurtransferase, E.C. 2.8.1.1) was purified from the nitrogen fixing organism Azotobacter vinelandii, and its amino acid composition was determined. The enzyme is a single polypeptide chain of M(r) 29,000 which showed an apparent pI of 4.7 and no presence of isoenzymes. Steady-state initial velocity measurements indicate that the enzyme catalyzes the transfer of sulfane sulfur of thiosulfate either to cyanide or to dihydrolipoate by way of a double displacement mechanism.