The kinetic behavior of rhodanese (thiosulfate: cyanide sulfurtransferase, EC 2.8.1.1) was investigated at pH values from 5.0 to 10.8. The binding of thiosulfate was shown to be dependent upon a pK’ of 9.9, with the protonated enzyme binding the substrate much more strongly than the deprotonated form. An enzymic nucleophile displaces sulfite to form the sulfur-substituted enzyme. This reaction ...

Several reports have indicated that there may be differences among the proteins responsible for a given enzymatic activity in difIerent tissues of the same animal (14). This paper reports the results of a comparative study of some biochemical properties of the enzyme rhodanese purified from the liver and the kidneys of the same steer. The two enyzmes have been found to be identical by all of th...

Evidence from gel filtration and sedimentation studies of crystalline bovine liver rhodanese indicated that the enzyme molecule of 37,000 molecular weight is a dimer. In the native state, this form is in rapid, pa-dependent equilibrium with the monomeric species. A stable dimer is formed under mild oxidizing conditions. Analysis of the protein by peptide mapping indicated that the monomers are ...

Mutants of rhodanese (EC 2.8.1.1) which substitute serine residues for each of the 4 cysteine residues have been studied to determine the roles of cysteines in the structure and function of the enzyme. The proteins compared in these studies were: the wild-type, C63S, C247S, C254S, C263S, C254S/C263S, and C63S/C254S/C263S. These current studies show that cysteine 247 is the only cysteine require...

ThiI has been identified as an essential enzyme involved in the biosynthesis of thiamine and the tRNA thionucleoside modification, 4-thiouridine. In Escherichia coli and Salmonella enterica, ThiI acts as a sulfurtransferase, receiving the sulfur donated from the cysteine desulfurase IscS and transferring it to the target molecule or additional sulfur carrier proteins. However, in Bacillus subti...