Radiation Chemical Reactions in Aqueous Oxygenated and Oxygen-Free Solutions of Aliphatic Dipeptides and Tripeptides

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Abstract
The principal radiation chemical reactions of simple peptides have been established based on analysis of the irradiated 11 peptide solutions. In oxygen-free solutions the main reactions are; Reductive deamination of the N-terminal amino acid yielding the acyl peptide and NH3; recombination between the radical of the acylpeptide and the original peptide or its radical leading to formation of a new C-C bond between CH, CH2 or CH3 groups of the 2 components; recombination between 2 radicals of the original peptide or a radical and a molecule on the same groups yielding neutral peptides linked by a diaminodicarboxylic acid; carboxy-lation on the same groups yielding acidic peptide. In oxygenated solutions the major reactions are Oxidative deamination of the N-terminal amino acid to the ketoacyl peptide, peptide bound cleavage by hydrolysis of the intermediary imine to NH3, CO2, the lower aldehyde from the N-terminal amino acid and to the C-terminal amino acid, or by formation of the amide of the N-terminal and the carbonyl derivative of the C-terminal amino acid. Minor reactions are oxidation of the methyl and methylene groups to the hydroxy derivatives, scission of the carbon chain and terminal decarboxylation.