Thiol---Disulfide Exchange Reagents

Disulfide exchange reactions occur over a broad range of conditions—from acid to basic pH—and in a wide variety of buffer constituents. Most crosslinking reactions involving disulfide exchange are done under physiological conditions or those most appropriate to maintain stability of the protein or other molecule being modified. 

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Figure 3.4 Outline of the synthesis of glycopolymer-peptide bioconjugate PGlcEMA-GSH via RAFT polymerisation and thiol-disulfide exchange. Reagents and conditions a) DTP, ethanolamine, acetonitrile, RT, 24 h and b) sodium methoxide, CHsCl/MeOH (1 1), RT, 1 h. Reproduced with permission from H. Shi, L. Liu, X. Wang and J. Li, Polymer Chemistry, 2012, 3, 1182. 2012, Royal Society of Chemistry [45]...

The four disulfide bonds of nine homologous short neurotoxins were cleaved by reduced dithiothreitol. The kinetics of refolding, induced by air reoxidation or in the presence of thiol-disulfide exchange reagents, indicated differences in refolding rates. Three toxins refolded 4-10 times more slowly than the six others. It was proposed from consideration of the sequence that a single additional amino acid insertion is responsible for these differences (Menez et al, 1980). These data indicate the role of noncovalent interactions in the formation of disulfide bridges. 

Similarly, Ellman s reagent [5,5 -dithiobis(2-nitrobenzoic acid)] can be used to activate one thiol-containing molecule by disulfide exchange and subsequently used to couple to a second sulfhydryl-containing molecule by the same mechanism (Chapter 1, Section 5.2) (Fig. 325). The disulfide of Ellman s reagent readily undergoes disulfide... 

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