Mercaptoethanol redox potential

Dithiothreitol (DTT) and dithioerythritol (DTE) are the trans and cis isomers of the compound 2,3-dihydroxy-1,4-dithiolbutane. The reducing potential of these versatile reagents was first described by Cleland in 1964. Due to their low redox potential (—0.33 V) they are able to reduce virtually all accessible biological disulfides and maintain free thiols in solution despite the presence of oxygen. The compounds are fully water-soluble with very little of the offensive odor of the 2-mercaptoethanol they were meant to replace. Since Cleland s original report, literally thousands of references have cited the use of mainly DTT for the reduction of cystine and other forms of disulfides. 

Many /x-oxo dimers are not stable under reducing conditions owing to instability of the n-oxo bridge moiety in either the mixed-valence or diferrous states. For example, [Fe(HBpz3)]20(0Ac)2 (HBpz3 is hydro-tris(pyrazolyl)borate) shows an electrochemical irreversible reduction wave even at very high scan rates (5 V/s) (13). The fact that the ascorbic acid does not show the same reactivity as 2-mercaptoethanol may be a consequence of differences in the redox potentials or the ability of the reductant to displace ligands and coordinate to the metal center. 

Zagal, J.H., M.A. Gulppi, C.A. Caro, and I.G. Cardenas-Jiron (1999). Paradoxical effect of the redox potential of adsorbed metaUophthalocyanines on their activity for the oxidation of 2-mercaptoethanol Inner versus outer sphere electrocatalysis. 

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