Studies on γ-irradiated aqueous solutions of tripeptides composed of glycine and L-alanine by the spin-trap high-performance liquid chromatography – electron spin resonance method

1984 ◽  
Vol 62 (11) ◽  
pp. 2206-2216 ◽  
Author(s):  
Fumio Moriya ◽  
Naohisa Iguchi ◽  
Keisuke Makino ◽  
Souji Rokushika ◽  
Hiroyuki Hatano
Keyword(s):  
Aqueous Solutions ◽  
High Performance ◽  
Spin Trap ◽  
Hydrogen Abstraction ◽  
Resonance Method ◽  
Side Chain ◽  
Carbonyl Groups ◽  
Spin Resonance ◽  
Hydrated Electrons ◽  
Electron Spin Resonance Method

The γ-irradiated aqueous solutions of four tripeptides were studied by the spin-trap hplc–esr method with 2-methyl-2-nitrosopropane. Four types of spin adducts were separated and identified as follows: (a) deamino adducts derived from short-lived radicals produced by reductive deaminations from the addition of hydrated electrons to the N-terminal peptide carbonyl groups, (b) C-terminal backbone adducts, (c) internal backbone adducts, and (d) side-chain adducts derived from short-lived radicals produced by hydrogen abstractions by hydroxyl radicals, mainly from so-called α-carbons in the C-terminal and internal main-chains and a carbon in an aliphatic side-chain, respectively. For polyglycine, internal backbone radicals produced by hydrogen abstraction were spin-trapped and detected.

Studies on γ-irradiated aqueous solutions of amino acids with functional groups by the spin-trap high-performance liquid chromatography – electron spin resonance method

1984 ◽  
Vol 62 (9) ◽  
pp. 1722-1730 ◽  
Author(s):  
Naohisa Iguchi ◽  
Fumio Moriya ◽  
Keisuke Makino ◽  
Souji Rokushika ◽  
Hiroyuki Hatano
Keyword(s):  
Amino Acids ◽  
High Performance Liquid Chromatography ◽  
Electron Spin Resonance ◽  
Aqueous Solutions ◽  
High Performance ◽  
Spin Trap ◽  
Resonance Method ◽  
The Other ◽  
Spin Resonance ◽  
Electron Spin Resonance Method

Aqueous solutions of L-glutamine, L-asparagine, sodium L-glutamate, sodium L-aspartate, L-serine, and L-threonine were γ-irradiated in the presence of a spin trap, 2-methyl-2-nitrosopropane. Stable spin adducts produced in the irradiated solutions were analyzed by the spin-trap hplc–esr method. The spin adducts of the following short-lived radicals were found and identified: H2NCOCH2CH2ĊHCOO− (1), [Formula: see text] and [Formula: see text] for L-glutamine; [Formula: see text] (2) for L-asparagine; −OOCCH2CH2ĊHCOO− (3) and [Formula: see text] for sodium L-glutamate; −OOCCH2ĊHCOO− (4) and [Formula: see text] (5) for sodium L-aspartate; [Formula: see text] and HOCH2ĊHCOO− (6) for L-serine; CH3CH(OH)ĊHCOO− (7) and [Formula: see text] for L-threonine. The free radicals, 1, 3, 4, 6, and 7, were due to the reaction of the hydrated electron [Formula: see text] with these amino acids and the other adducts were due to the attack of hydroxyl radical (•OH). The two diastereomeric pairs of spin adducts of the short-lived radicals, 2 and 5, could be individually separated by the technique utilized.

FREE RADICALS OF BIOLOGICAL INTEREST: PART II. ELECTRON SPIN RESONANCE (ESR) SPECTRA OF 2537 A IRRADIATED AMINO ACIDS

1967 ◽  
Vol 45 (12) ◽  
pp. 1831-1839 ◽  
Author(s):  
W. F. Forbes ◽  
P. D. Sullivan
Keyword(s):  
Amino Acids ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Hydrogen Abstraction ◽  
Esr Spectra ◽  
Side Chain ◽  
Biological Interest ◽  
Spin Resonance ◽  
Cyclohexadienyl Radical ◽  
Secondary Radical

Polycrystalline amino acids, when irradiated with 2537 Å light, afford a variety of electron spin resonance signals. These signals are generally stable at room temperature for relatively long periods of time. For a number of the spectra obtained, there is evidence that more than one radical species contributes to the observed spectra. The signals obtained frequently differ from those obtained on exposure to ionizing radiation. The postulated species formed can often be visualized as being formed by effective hydrogen abstraction from the alkyl-substituted tertiary carbon atom or from the —OH, —SH or —NH group contained in the side chain. For L-phenylalanine a secondary radical is obtained, which is ascribed to a cyclohexadienyl radical.

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