Diamide: An oxidant probe for thiols

Research output: Contribution to journalComment/debate


The most convenient and chemically simple agent—diamide—is capable of producing a rapid diminution of the tripeptide thiol—glutathione (GSH)—within erythrocytes. An oxidant probe changes the oxidation state of the system; in the present case, diamide is an oxidant probe for thiols and changes the oxidation state of the thiols. Diamide perturbs the thiol status of a system. In most cases, the system can return to its original state by reduction. Information about the role of thiols in the biochemical, biophysical, and physiological economy of a biological system can be gained by the treatment of a system with an oxidant probe for thiols. The reaction of diamide with thiols can be followed spectrophotometrically between 300 and 325 nm and yields a second-order rate constant. The reduction of the diazene forms the diazane dicarboxylic acid bis(N,N-dimethylamide), a hydrazide that does not absorb down to 230 nm. The reaction of thiols with diazenecarbonyl derivatives—such as diamide—occurs in two observable stages, with thiolate anions (RS) as the reactive species. The reaction proceeds via addition and displacement steps. In the case of GSH, the GS anion adds to the diazene double bond to form a sulfenylhydrazine, which, in a second step, reacts with a second GS anion at sulfur to yield a disulfide and a hydrazine.

Original languageEnglish
Pages (from-to)123-133
Number of pages11
JournalMethods in Enzymology
Issue numberC
StatePublished - 1 Jan 1995


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