Protein Antioxidants: Reducing Agents DTT and DTE

DTT (dithiothreitol, Cleland's reagent) and DTE (dithioerythritol) are protein antioxidants that protect cysteine-containing proteins from being oxidized and are thus integral components of buffers used in protocols for the isolation and purification of proteins.

Sulfhydryl groups in proteins originate from cysteine residues within the amino acid sequence. Cysteine readily dimerizes oxidatively to cystine. This oxidation involves the formation of disulfide bridges either within, or between proteins. These disulfide bridges can significantly affect protein folding which consequently impacts the secondary, tertiary and quaternary structure of the protein. For this reason, biological activity is often lost in the process of oxidation.

The sulfhydryl groups of DTT and DTE are oxidized more readily than those of protein-based cysteine. Thus, if an oxidation of cysteine to cystine has occured, DTT and DTE can reverse the process by breaking up the disulfide bridge and reducing cystine back to cysteine. Concurrently, the sulfhydryl groups of DTT or DTE are oxidized, thus regenerating the biological activity of cysteine-containing proteins that had previously been deactivated by oxidation. It should be noted that DTT and DTE will denature any proteins containing naturally occurring disulfide bridges. For this reason, these reagents are widely used in SDS-electrophoresis.

The mechanism of DTE breaking up the disulfide bridge and reducing cystine back to cysteine.

1. Cleland, W.W. Biochemistry 1964, 3, 480.
2. Zahler, W.L; Cleland, W.W. J. Biol. Chem. 1968, 243, 716.
3. Rüegg, U.T.; Rudinger, J. Meth. Enzymol. 1977, 47, 111.
4. Lauriault, V.V.M.; O'Brien, P.J. Mol. Pharmacol. 1991, 40, 125.
5. Rüegg, U.T.; Rudinger, J. Methods Enzymol. 1977, 47, 111.
6. Lane L.C. Anal. Biochem. 1978, 86, 655.
7. Beilstein Beil.1, III, 2359.

Selected Biosynth products
Cat.No. - Product Name
D-8200 - 1,4-Dithiothreitol
D-8220 - L-1,4-Dithiothreitol
D-8100 - 1,4-Dithioerythritol

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