Studies on spin-trapped radicals in. gamma. -irradiated aqueous solutions of L-alanylglycine and L-alanyl-L-alanine by high-performance liquid chromatography and ESR spectroscopy

Journal Article · Tue Feb 09 23:00:00 EST 1982 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00367a030· OSTI ID:5113785

Moriya, F; Makino, K; Suzuki, N; Rokushika, S; Hatano, H

Aqueous solutions of L-alanylglycine and L-alanyl-L-alanine were ..gamma.. irradiated in the presence of a spin trap, 2-methyl-2-nitrosopropane. Stable sspin adducts produced in the ..gamma..-irradiated solutions were analyzed by high-performance liquid chromatography and ESR spectroscopy. The following spin adducts were found and identified: t-BuN(O)CH-(CH/sub 3/)CONHCH/sub 2/COO/sup -/ (I), NH/sub 3//sup +/-*CH(CH/sub 3/)CONH-*CH(COO/sup -/)N(0)-t-Bu (II), and t-BuN(0)CH/sub 2/CH(NH/sub 3//sup +/)-CONHCH/sub 2/COO/sup -/(III) from L-alanylglycine; t-BuN(0)-*CH(CH/sub 3/)CONH-*CH(CH/sub 3/)COO/sup -/ (IV), NH/sub 3//sup +/-*CH(CH/sub 3/)-CONH-*C(CH/sub 3/)(COO/sup -/)N(0)-t-Bu (V), NH/sub 3//sup +/CH(CH/sub 3/)CONHCH(COO/sup -/)CH/sub 2/N(O)-t-Bu (VI), and t-Bu-N(0)-CH/sub 2/CH(NH/sub 3//sup +/)CONHCH(CH/sub 3/)COO/sup -/ (VII) from L-alanyl-L-alanine. Each of sspin adducts II, IV, and V was found as a pair of diastereomeric radicals, which revealed mutually different hyperfine splitting constants. The two diastereomeric pairs of spin adducts II and V were individually separated. It was demonstrated that ESR spectra of spin adducts II, III, and VI changed remarkably with pH through the acid-dissociation equilibria of the carboxyl or amino groups. The pK/sub a/ values for the dissociation have been determined to be 1.8 and 1.6 for the carboxyl groups of the pair of diastereomeric pin adducts II. The pK/sub COOH/ values are lower than that of alanylglycine because of the electron-withdrawing character of the nitroxyl group. 12 figures, 2 tables.

• Research Organization: Kyoto Univ., Japan
• OSTI ID: 5113785
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 104:3; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ABSORPTION SPECTRA
ADDUCTS
AMINO ACIDS
AQUEOUS SOLUTIONS
CARBOXYLIC ACIDS
CHEMICAL ANALYSIS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHEMISTRY
CHROMATOGRAPHY
COMPUTERIZED SIMULATION
DATA
DECOMPOSITION
DISPERSIONS
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
EXPERIMENTAL DATA
GAMMA RADIATION
INFORMATION
IONIZING RADIATIONS
KINETICS
LIQUID COLUMN CHROMATOGRAPHY
MAGNETIC FIELDS
MAGNETIC RESONANCE
MATHEMATICAL MODELS
MATHEMATICS
MIXTURES
NITROSO COMPOUNDS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PEPTIDES
PH VALUE
PROTEINS
QUANTITATIVE CHEMICAL ANALYSIS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADIOLYSIS
REACTION KINETICS
RESONANCE
SEPARATION PROCESSES
SIMULATION
SOLUTIONS
SPECTRA
STRUCTURAL CHEMICAL ANALYSIS
TRAPPING
YIELDS