Differentiation of the roles of sulfide oxidase and rhodanese in the detoxification of sulfide by the colonic mucosa.
OBJECTIVE
Identify the roles of sulfide oxidase and rhodanese in sulfide detoxification in rat colonic mucosa.


RESULTS
Gel filtration of colonic mucosa and purified bovine rhodanese showed that rhodanese and sulfide oxidizing activities resided in different proteins. In the presence of cyanide, rhodanese shifted the major mucosal metabolite of sulfide from thiosulfate to thiocyanate. The purported ability of purified rhodanese to metabolize sulfide reflects: (a) contamination with a sulfide oxidase, and (b) the spontaneous conversion of sulfide to thiosulfate during storage; rhodanese then catalyzes the conversion of this thiosulfate to thiocyanate.


CONCLUSIONS
Rhodanese does not metabolize sulfide. The rate-limiting step in sulfide detoxification is oxidation by a sulfide oxidase to thiosulfate. Rhodanese then converts this thiosulfate to thiocyanate, but this reaction does not increase the rate of sulfide detoxification. The recent use of rhodanese activity as a surrogate for the rate that colonic mucosa detoxifies sulfide is inappropriate.
Wilson
Kirk
K
Research Service (151) Mpls, Veterans Affairs Medical Center (VAMC), Minneapolis, MN 55417, USA.
Mudra
Mitchell
M
Furne
Julie
J
Levitt
Michael
M
D000818:Animals; D003106:Colon / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D003108:Colonic Diseases / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D004591:Electrophoresis, Polyacrylamide Gel; D008658:Inactivation, Metabolic; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008297:Male; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013053:Spectrophotometry; D013440:Sulfides / Q000493:pharmacokinetics*; D013884:Thiosulfate Sulfurtransferase / Q000378:metabolism*
D013440:Sulfides; D050862:Oxidoreductases Acting on Sulfur Group Donors; C080499:sulfide oxidase; D013884:Thiosulfate Sulfurtransferase