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The unusual hydrogen‐deuterium exchange of α ‐carbon protons in N ‐substituted glycine‐containing peptides
Author(s) -
Bąchor Remigiusz,
Setner Bartosz,
Kluczyk Alicja,
Stefanowicz Piotr,
Szewczuk Zbigniew
Publication year - 2014
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/jms.3318
Subject(s) - chemistry , sarcosine , hydrogen–deuterium exchange , aqueous solution , deuterium , electrospray ionization , racemization , amino acid , amide , peptide , residue (chemistry) , medicinal chemistry , stereochemistry , hydrogen , combinatorial chemistry , organic chemistry , glycine , ion , biochemistry , physics , quantum mechanics
Hydrogens connected to α ‐carbon ( α ‐C) of amino acid residues are usually resistant to hydrogen‐deuterium exchange (HDX) unless reaction conditions promote racemization. Although N ‐methylglycine (sarcosine) residue has been found in biologically active peptide such as cyclosporine, to the best of our knowledge, the HDX of α ‐C protons of this residue was not explored yet. Here, we presented a new and efficient methodology of α ‐C deuteration in sarcosine residues under basic aqueous conditions. The deuterons, introduced at α ‐C atom, do not undergo back‐exchange in acidic aqueous solution. The electrospray ionization‐MS and MS/MS experiments on proposed model peptides confirmed the HDX at α ‐C and revealed the unexpected hydrogen scrambling in sarcosine‐containing peptides. Although the observed HDX of α ‐C protons is only successful in N ‐acylglycine when the amide possesses a certain degree of alkylation, it offers a new approach to the analysis of sarcosine‐containing peptides such as cyclosporine. Copyright © 2014 John Wiley & Sons, Ltd.