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.
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.
Encinar
Jorge Ruiz
JR
CNRS UMR 5034, Hélioparc, 2 Av. Pr. Angot, F-64053 Pau, France.
Ruzik
Rafal
R
Buchmann
William
W
Tortajada
Jeanine
J
Lobinski
Ryszard
R
Szpunar
Joanna
J
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*
D018036:Selenium Compounds