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Electron impact fragmentation of oxazoles and oxazinones derived from leucine and isoleucine
Author(s) -
Jayasimhulu K.,
Day R. A.
Publication year - 1980
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.1200070103
Subject(s) - isoleucine , fragmentation (computing) , leucine , chemistry , degradation (telecommunications) , ion , yield (engineering) , mass spectrum , electron ionization , amino acid , stereochemistry , medicinal chemistry , organic chemistry , biochemistry , physics , biology , thermodynamics , telecommunications , computer science , ionization , ecology
Differentiation between leucine and isoleucine was effected utilizing derivatives obtained by degradation of peptides by two novel reactions. The two reactions are (1) the random degradation by treatment with, first, 2‐pyridinecarboxaldehyde yielding α‐keto derivatives which are subsequently converted to oxazinones, and (2) the N‐terminal sequential degradation of peptides effected by vic ‐dicarbonyl compounds which yield characteristic oxazinones in one procedural step. The mass spectra of the oxazinones produced by leucine‐ and isoleucine‐containing peptides via either degradation leads to characteristic oxazinones which give unique fragmentation patterns. The one from isoleucine gave intense ions at m/z 253, 225 and 197; from leucine at m/z 253, 225 and 183. The ions at m/z 183 and 197 provided the largest differences, but other fragment ions contributed to the differentiation.