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Identification of tyrosine sulfation in Conus pennaceus conotoxins α‐PnIA and α‐PnIB: further investigation of labile sulfo‐ and phosphopeptides by electrospray, matrix‐assisted laser desorption/ionization (MALDI) and atmospheric pressure MALDI mass spectrometry
Author(s) -
Wolfender JeanLuc,
Chu Feixia,
Ball Haydn,
Wolfender Florence,
Fainzilber Michael,
Baldwin Michael A.,
Burlingame Alma L.
Publication year - 1999
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/(sici)1096-9888(199904)34:4<447::aid-jms801>3.0.co;2-1
Subject(s) - chemistry , mass spectrometry , chromatography , sulfation , electrospray ionization , matrix assisted laser desorption/ionization , protein mass spectrometry , tandem mass spectrometry , desorption , organic chemistry , biochemistry , adsorption
Liquid chromatography/electrospray ionization mass spectrometrywas used to investigate the peptide composition of the venom of Conus pennaceus , a molluscivorous cone shell from the Red Sea.Based on observed M r s, this venom contained allknown conotoxins previously isolated and identified from thisspecies. Interestingly, the doubly protonated species of only two ofthese conotoxins, α‐PnIA and α‐PnIB, showedadditional related ions at +40 m / z (+80 Da), indicating the presence of either sulfationor phosphorylation in both components. High‐performance liquidchromatographic (HPLC) fractions containing these twoconotoxins were examined by matrix‐assisted laserdesorption/ionization (MALDI) mass spectrometry in bothpositive and negative ion modes, as well as by MALDIhigh‐energy collision‐induced dissociation. Theseexperiments established the presence of a single sulfated tyrosineresidue within both α‐PnIA and α‐PnIB.Hence their post‐translationally modified sequences areGCCSLPPCAANNPDY(S)C‐NH 2 (α‐PnIA) andGCCSLPPCALSNPDY(S)C‐NH 2 (α‐PnIB). This assignment was supported bycomparison of their mass spectral behavior with that of knownsulfated and phosphorylated peptides. This data clarified further thedistinguishing features of the ionization and fragmentation of suchmodified peptides. Selective disulfide folding of syntheticα‐PnIB demonstrated that both sulfated andnon‐sulfated toxins co‐elute on reversed‐phaseHPLC and that α‐PnIB possesses the same disulfideconnectivity as other ‘classical’α‐conotoxins reported previously. Copyright © 1999John Wiley & Sons, Ltd.