R. Mintel, J. Westley
Jul 25, 1966
Citations
0
Influential Citations
49
Citations
Journal
The Journal of biological chemistry
Abstract
Abstract Kinetic studies comparing methanethiosulfonate and thiosulfate as rhodanese substrates have shown that the cleavage of the thiosulfate sulfur-sulfur bond limits the over-all maximum velocity of the thiosulfate-cyanide sulfur transfer reaction. A kinetically significant enzyme-thiosulfate complex has thus been shown. The same studies have indicated that the Michaelis constant for thiosulfate is a true dissociation constant for this complex. Infrared spectral studies and experiments involving the reaction between thiosulfonates and cyanide in nonenzymic systems have shown that the reactivity of the planetary sulfur atom toward cyanide is enhanced by a shift of electrons away from the sulfur-sulfur bond. Studies of the enzyme-catalyzed reaction between the thiosulfonates and cyanide have suggested that one aspect of enzymic catalysis in the thiosulfate reaction is such a shift of electrons away from the sulfur-sulfur bond. A basis for the anomalous behavior of aromatic substrates has been discussed.