Journal of Biochemistry Advance Access originally published online on February 22, 2008
Journal of Biochemistry 2008 143(5):685-693; doi:10.1093/jb/mvn023
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© 2008 The Japanese Biochemical Society.
Interaction of Glutathione and Sodium Selenite In vitro Investigated by Electrospray Ionization Tandem Mass Spectrometry
1Department of Chemistry of Yanbian University, Key Laboratory of Organism Functional Factor of the Changbai Mountain, Ministry of Education Yanji, 133002, China; and 2Department of Chemistry, Changwon National University, Changwon 641-773, Korea
*To whom correspondence should be addressed. Tel: +82-55-213-3436, Fax: +82-55-213-3439, E-mail: yilee.kr{at}gmail.com
Received January 23, 2008; Accepted February 8, 2008
| Abstract |
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Selenite has been found to be an active catalyst for the oxidation of sulphhydryl compounds, such as glutathione (GSH). Considering the biological importance of GSH oxidation and the implication of sulphhydryl compounds in selenium poisoning and other biological activities, more information on selenite oxidation of GSH in enzyme-free conditions is desirable. Herein, we describe glutathione and sodium selenite simply mixed in aqueous solutions. The interaction products and transient intermediate are identified and characterized using electrospray ionization (ESI) tandem mass spectrometry. In the first step, GSH directly reacts to form diglutathione (GSSG) and unstable selenodiglutathione (GS-Se-SG). Then selenodiglutathione further reacted with remaining GSH to form diglutathione and elemental selenium, Se0. As the amount of GSSG significantly increased or acidity of the solution increased, the redox potential of glutathione [E0'(GSSG/2GSH)
–250 mV (NHE)] significantly shifted to the positive direction. This makes the GSSG react with elemental selenium formed in the solution, which can be demonstrated by another unstable intermediate ion identified at m/z 418 by mass spectrometry with the elemental composition of [GSS-Se]–. The reaction mechanism between GSH and sodium selenite has been proposed according to the ESI-MS, NMR and UV-vis spectrometric measurements.
Key Words: selenium, glutathione, sodium selenite; selenodiglutathione, electrospray ionization tandem mass spectrometry
Abbreviations: GSH, Glutathione; GSSG, diglutathione; GS-Se-SG, selenodiglutathone; NHE, normal hydrogen electrode; RS-Se-SR, selenodisulfide; GS-Se-, selenopersulfide; DNA, deoxyribonucleic acid; ESI, electrospray ionization; MS, mass spectrometry; NMR, nuclear magnetic resonance; UV-Vis, ultraviolet-visible