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Differentiation of α‐ from γ‐glutamyl dipeptides by chemical ionization mass spectrometry
Author(s) -
Nagasawa Herbert T.,
Magnan Sanne D. J.,
Foltz Rodger L.
Publication year - 1982
Publication title -
biomedical mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0306-042X
DOI - 10.1002/bms.1200090606
Subject(s) - protonation , dipeptide , chemistry , derivatization , mass spectrometry , amino acid , molecule , chemical ionization , ion , peptide , electrospray ionization , ionization , stereochemistry , chromatography , organic chemistry , biochemistry
Chemical ionization mass spectrometry has been shown to be a useful method for the differentiation of α‐ and γ‐glutamyl dipeptides where the C‐terminal amino acids are simple α‐amino or α‐imino acids without additional functional groups. The α‐glutamyl dipeptides lost one and two molecules of H 2 O from the protonated molecular ion to give fragment ions at [MHH 2 O] + and [MH2H 2 O] + . With the γ‐glutamyl dipeptides, the characteristic fragment ions of highest intensities were the protonated pyroglutamic acid (pyrrolidone‐5‐carboxylic acid) ion at m / z 130, and a fragment ion corresponding to the protonated C‐terminal amino acid. The procedure does not require derivatization of the dipeptide, and because only small sample sizes are needed it could prove useful for the characterization of synthetic samples and glutamyl dipeptides isolated and purified from biological sources.