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

J.R. Encinar (1) , R. Ruzik , W. Buchmann , J. Tortajada , Ryszard Lobinski (1) , Joanna Szpunar (1)

1 LCABIE - Laboratoire de Chimie Analytique Bio-Inorganique et Environnement

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.

Domaines: Chimie analytique

J.R. Encinar, R. Ruzik, W. Buchmann, J. Tortajada, Ryszard Lobinski, et al.. 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. Analyst, 2003, 128 (3), pp.220-224. ⟨10.1039/b212262f⟩. ⟨hal-00291370⟩