In 1959 Ellman1 introduced 5,5'-dithio-bis-(2-nitrobenzoic acid), also known as DTNB, as a versatile water-soluble compound for quantitating free sulfhydryl groups in solution. A solution of this compound produces a measurable yellow-colored product when it reacts with sulfhydryls. Consequently, Ellman’s Reagent (DTNB) test has been used as a method to estimate sulfhydryls in solution.1 A method for the determination of free thiols for small peptides and proteins synthesized using standard solid phase synthetic methods. Peptides from these syntheses are usually in their reduced form, and are usually stable to oxidation in acidic solutions. Free thiol can be determined in solutions collected from chromatographic separations or from reconstituted lyophilized samples.
Reference
- Ellman, G.L. (1959) Tissue sulfhydryl groups. Arch. Biochem. Biophys. 82, 70-7.