The chemistry of peptides related to metabolites of Trichoderma Spp. 3. An unusual dehydration reaction of 2-methylalanine peptides after electron impact ionization

Autor:	W. D. Jamieson, A. Taylor
Rok vydání:	1986
Předmět:	Chemical ionization Chemistry Stereochemistry Organic Chemistry General Chemistry Mass spectrometry Photochemistry Catalysis Reaction rate Residue (chemistry) Dehydration reaction Ionization Mass spectrum Electron ionization
Zdroj:	Canadian Journal of Chemistry. 64:277-284
ISSN:	1480-3291 0008-4042
DOI:	10.1139/v86-047
Popis:	Peptides of 2-methylalanine, where this residue is not the C-terminus, give molecular ions of low abundance on electron impact ionization, but abundant ions are formed by loss of the elements of water from the molecular ion. The dehydration reaction does not occur in permethylated derivatives, nor under the milder ionization conditions in the chemical ionization source. The reaction does not appear to be time or temperature dependent, but depends on the steric hindrance of the NH group of the 2-methylalanine residue. The reaction occurs at sites where 2-methylalanine is not the C-terminal amino acid. In the cases of two pentapeptides where the dehydration reaction was of high probability, the correct sequence was found by semi-quantitative measurements of reaction rates in the first field-free region of a double focussing mass spectrometer.
Databáze:	OpenAIRE
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