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Promotion and Stabilization of b 1 ions in Peptide Phenythiocarbamoyl Derivatives: Analogies with Condensed‐phase Chemistry
Author(s) -
Summerfield Scott G.,
Bolgar Mark S.,
Gaskell Simon J.
Publication year - 1997
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(199702)32:2<225::aid-jms471>3.0.co;2-#
Subject(s) - chemistry , ion , phase (matter) , peptide , stereochemistry , combinatorial chemistry , computational chemistry , organic chemistry , biochemistry
The preparation of the N ‐terminal phenylthiocarbamoyl (PTC) derivative is the first step in the condensed phase chemistry employed in the Edman method for peptide sequencing; subsequent treatment with anhydrous acid effects cleavage of the N ‐terminal peptide bond yielding a derivatized amino acid and a truncated peptide. Low‐energy collisional activation of peptide PTC derivative [M+2H] 2+ ions during electrospray tandem mass spectrometry results in highly favoured cleavage of the N ‐terminal peptide bond yielding complementary b 1 and y n‐1 fragments. The cleavage is evidently promoted by protonation of the peptide backbone. The apparently close mechanistic similarity between the gas‐phase and condensed‐phase processes may be readily understood in terms of current thinking concerning the mechanism of formation of b‐type ions, which involves nucleophilic attack by an N ‐terminal carbonyl moiety on the carbonyl carbon of the first peptide bond. Collisionally activated decomposition of source‐formed b 1 ions from a peptide PTC derivative is consistent with ion rearrangement similar to the PTC–phenylthiohydantoin isomerization observed in the condensed phase. © 1997 by John Wiley & Sons, Ltd.