Electron spin resonance study of. gamma. -irradiated frozen aqueous solutions containing N-acetylamino acids

Journal Article · Thu Nov 01 04:00:00 EST 1979 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100485a017· OSTI ID:5739217

Sevilla, M D; D'Arcy, J B; Morehouse, K M

The results of ..gamma.. irradiation of a number of N-acetylamino acids at 77 K in frozen D/sub 2/O and H/sub 2/O solutions are reported. The radicals produced by the irradiation, their relative amounts, and their stability were studied as a function of temperature. The results found for ices of N-acetylalanine illustrate the reaction mechanisms found. At low temperatures (120 K) the peptide anion and decarboxylated species dominate the spectrum. Upon warming to 190 K the anion converts to the amide and fatty acid radical by secondary deamination: CH/sub 3/CO/sup -/NDCH(CH/sub 3/)CO/sub 2//sup -/ + D/sup +/ ..-->.. CH/sub 3/COND/sub 2/ + .CH(CH/sub 3/)CO/sub 2//sup -/. Further warming to 220 K results in abstraction of the intermediate radicals from the parent compound to form the ..cap alpha..-carbon radical: CH/sub 3/CHCO/sub 2//sup -/ + CH/sub 3/CONDCH(CH/sub 3/)CO/sub 2//sup -/ ..-->.. CH/sub 3/CH/sub 2/CO/sub 2//sup -/ + CH/sub 3/CONDCCH/sub 3/CO/sub 2//sup -/. Results found for N-acetylglutamic acid show similar reactions and also show evidence for electron attachment to the two carboxyl groups as well as the peptide linkage. An investigation as a function of pD shows that the site of electron attachment is strongly pD dependent with the carboxyl groups being favored at low pD and the peptide linkage favored at high pD. 9 figures, 1 table.

• Research Organization: Oakland Univ., Rochester, MI
• OSTI ID: 5739217
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 83:22; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
AMIDES
AMINO ACIDS
ANIONS
AQUEOUS SOLUTIONS
CARBOXYLIC ACIDS
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DEAMINATION
DECOMPOSITION
DISPERSIONS
ELECTROMAGNETIC RADIATION
ELECTRON ATTACHMENT
ELECTRON SPIN RESONANCE
FREEZING
GAMMA RADIATION
HEAVY WATER
HYDROGEN COMPOUNDS
IONIZING RADIATIONS
IONS
IRRADIATION
LOW TEMPERATURE
MAGNETIC RESONANCE
MIXTURES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PEPTIDES
PROTEINS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOLYSIS
RESONANCE
SOLUTIONS
TEMPERATURE DEPENDENCE
WATER