Identification and Synthesis of a Novel Selenium−Sulfur Amino Acid Found in Selenized Yeast:  Rapid Indirect Detection NMR Methods for Characterizing Low-Level Organoselenium Compounds in Complex Matrices

Eric Block,† Richard S. Glass,*‡ Neil E. Jacobsen,‡ Sherida Johnson,† Chethaka Kahakachchi,§ Rafal Kamiński,‡ Alexandra Skowrońska, Harriet Totoe Boakye,§ Julian F. Tyson,§ and Peter C. Uden§
Departments of Chemistry, University at Albany, State University of New York, Albany, New York 12222; The University of Arizona, Tucson, Arizona 85721; University of Massachusetts, Amherst, Massachusetts 01003; and Center of Molecular and Macromolecular Studies, Polish Academy of Sciences, 90-363 Lodz, Poland
J. Agric. Food Chem., 2004, 52 (12), pp 3761–3771
DOI: 10.1021/jf049887z
Publication Date (Web): May 21, 2004
Copyright © 2004 American Chemical Society
†

 University at Albany, State University of New York.

,
*

 To whom correspondence should be addressed. Phone:  (520) 621-2939. E-mail:  rglass@u.arizona.edu.

,
‡

 The University of Arizona.

,
§

 University of Massachusetts.

,

 Polish Academy of Sciences.

Abstract

After proteolytic digestion, aqueous extraction, and derivatization with diethyl pyrocarbonate or ethyl chloroformate, HPLC−inductively coupled plasma (ICP)-MS, GC−atomic emission detection (AED), and GC−MS analysis of high-selenium yeast stored at room temperature for more than 10 years showed selenomethionine as the major Se product along with substantial amounts of selenomethionine selenoxide hydrate and the previously unreported selenoamino acid having a Se−S bond, S-(methylseleno)cysteine. The identity of the latter compound was confirmed by synthesis. The natural product was shown to be different from a synthetic sample of the isomeric compound Se-(methylthio)selenocysteine. Selenium-specific NMR spectroscopic methods were developed to directly analyze the aqueous extracts of the hydrolyzed selenized yeast without derivatization or separation. Selenomethionine and S-(methylseleno)cysteine were identified by 77Se−1H HMQC−TOCSY experiments.

Keywords: Selenized yeast; selenoamino acids; S-(methylseleno)cysteine; 1D HMQC−TOCSY

View: Full Text HTML | Hi-Res PDF

Tools

History

  • Published In Issue June 16, 2004
  • Received for review January 21, 2004. Revised manuscript received April 9, 2004. Accepted April 13, 2004. Partial support was provided by the National Science Foundation (NSF Grant CHE-9906566 (E.B.), NSF Grant 0094568 (J.F.T.)), the Petroleum Research Fund, administered by the American Chemical Society (E.B.), and the Colon Cancer Prevention Program Project funded by the National Institutes of Health (Grant CA-41108 (R.S.G., R.K.)).

Recommend & Share