Kinetics and mechanism of the glutathione-dependent reduction of dehydromethionine.
Dehydromethionine (S-methylisothiazolidine-3-carboxylic acid) is reduced by glutathione (aqueous solution, 25 degrees C) to give methionine and glutathione disulfide in a reaction that is dependent on pH and the nature and concentration of the buffer utilized. The data are consistent with proton-assisted, rate-limiting attack of glutathione thiolate anion on the sulfilimine sulfur with concomitant cleavage of the sulfur-nitrogen bond. The data predict a half-life for dehydromethionine ranging between 33 and 330 min in the presence of physiological concentrations of glutathione and phosphate buffer, suggesting that dehydromethionine and similar sulfilimines may have a sufficient lifetime in vivo to permit their use as carriers of oxidizing equivalents.
Young
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PR
Department of Chemistry, University of Illinois, Chicago 60680.
Briedis
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AV
D000465:Algorithms; D002021:Buffers; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D019803:Glutathione Disulfide; D006207:Half-Life; D007700:Kinetics; D010084:Oxidation-Reduction; D013844:Thiazoles / Q000378:metabolism*; D013997:Time Factors
D002021:Buffers; D013844:Thiazoles; C057796:dehydromethionine; D005978:Glutathione; D019803:Glutathione Disulfide