title: Detection of selenocompounds in a tryptic digest of yeast selenoprotein by MALDI time-of-flight MS prior to their structural analysis by electrospray ionization triple quadrupole MS.
abstract: MALDI-TOFMS was proposed as a key technique to a novel generic approach for the speciation analysis of selenium in yeast supplements. Owing to a lower detection limit and superior matrix tolerance to electrospray MS it allowed a successful detection of selenocompounds in samples for which electrospray MS had failed. The analytical approach developed was applied to the identification of a previously unreported selenopentapeptide (m/z 596) in the tryptic digest of a water-soluble selenoprotein fraction isolated by size-exclusion chromatography. The information on the mass of the protonated molecular ion obtained from MALDI allowed the optimization of the conditions for collision induced dissociation MS using a triple quadrupole spectrometer that enabled the determination of the amino acid sequence SeMet-Asn-Ala-Gly-Arg of the selenopeptide.
authors.affiliation: CNRS UMR 5034, Hélioparc, 2 Av. Pr. Angot, F-64053 Pau, France.
authors.forename: Jorge Ruiz
authors.initials: JR
authors.lastname: Encinar
authors.forename: Rafal
authors.initials: R
authors.lastname: Ruzik
authors.forename: William
authors.initials: W
authors.lastname: Buchmann
authors.forename: Jeanine
authors.initials: J
authors.lastname: Tortajada
authors.forename: Ryszard
authors.initials: R
authors.lastname: Lobinski
authors.forename: Joanna
authors.initials: J
authors.lastname: Szpunar
mesh_terms: D019587:Dietary Supplements; D018036:Selenium Compounds / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D015002:Yeast, Dried / Q000737:chemistry*
chemical_list: D018036:Selenium Compounds