title: 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.
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.
authors.affiliation: Department of Chemistry, University at Albany, State University of New York, Albany, New York 12222, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Block
authors.forename: Richard S
authors.initials: RS
authors.lastname: Glass
authors.forename: Neil E
authors.initials: NE
authors.lastname: Jacobsen
authors.forename: Sherida
authors.initials: S
authors.lastname: Johnson
authors.forename: Chethaka
authors.initials: C
authors.lastname: Kahakachchi
authors.forename: Rafal
authors.initials: R
authors.lastname: Kamiński
authors.forename: Alexandra
authors.initials: A
authors.lastname: Skowrońska
authors.forename: Harriet Totoe
authors.initials: HT
authors.lastname: Boakye
authors.forename: Julian F
authors.initials: JF
authors.lastname: Tyson
authors.forename: Peter C
authors.initials: PC
authors.lastname: Uden
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000031:analogs & derivatives* / Q000032:analysis* / Q000138:chemical synthesis*; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D013058:Mass Spectrometry; D016566:Organoselenium Compounds / Q000032:analysis* / Q000138:chemical synthesis*; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D012643:Selenium / Q000032:analysis*; D017279:Selenocysteine / Q000031:analogs & derivatives
chemical_list: D016566:Organoselenium Compounds; D017279:Selenocysteine; D012643:Selenium; D003545:Cysteine; C002979:selenomethylselenocysteine