Electron spin resonance of spin trapped radicals in γ-irradiated polycrystalline dipeptides. Chromatographic separation of radicals

1982 ◽  
Vol 60 (12) ◽  
pp. 1480-1485 ◽  
Author(s):  
Keisuke Makino ◽  
Peter Riesz
Keyword(s):  
High Performance Liquid Chromatography ◽  
Electron Spin Resonance ◽  
Ring Opening ◽  
High Performance ◽  
Room Temperature ◽  
Spin Trap ◽  
Esr Spectra ◽  
Spin Resonance ◽  
Carboxyl Terminal ◽  
Deamination Reaction

Polycrystalline dipeptides (glycyl-glycine, glycyl-L-valine, glycyl-L-leucine, L-alanyl-glycine, and L-prolyl-L-alanine) were γ-irradiated at room temperature in the absence of air. Subsequently they were dissolved in aqueous solutions containing 2-methyl-2-nitrosopropane as the spin trap. From the esr spectra of the nitroxide radicals separated by high-performance liquid chromatography, structural assignments of the radicals were made. For glycyl peptides, H-abstraction from the α-carbon atoms of the carboxyl terminal residues and from the side-chains were observed. For L-alanyl-glycine, H-abstraction from the glycyl residue and the formation of the deamination radical could be shown to occur. For L-prolyl-L-alanine, the ring opening (deamination) reaction, decarboxylation and H-abstraction from the C-terminal a-carbon were seen.

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.

scholarly journals A new method for determining the concentration of vanadyl ions in clays

2011 ◽  
Vol 62 (2) ◽  
pp. 181-186 ◽  
Author(s):  
Pavle Premović ◽  
Budimir Ilić ◽  
Dragan Đorđević
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Room Temperature ◽  
Esr Spectra ◽  
New Method ◽  
Simple Method ◽  
Routine Work ◽  
Spin Resonance ◽  
Resonance Data ◽  
Electron Spin Resonance Data

A new method for determining the concentration of vanadyl ions in claysA novel and simple method for quantitatively determining the concentration of vanadyl ions in clays using electron spin resonance data has been developed. Several vanadyl standards with concentrations between 200-1000 ppm were prepared in a mixture of glycerol and kaolinite (KGa-2). The anisotropic electron spin resonance (ESR) spectra were recorded at room temperature, and the specific intensity of the line (attributed to nuclear spin m = -5/2||) was determined. For vanadyl concentrations between 50 ppm and 200 ppm, the standards must be prepared by mixing kaolinite with known vanadyl content (FBT2A-03) and kaolinite (GB1) containing no vanadyl. The method is applicable without modification to other clays and clay-rich sediments containing vanadyl ions. The whole procedure is very suitable for routine work.

scholarly journals Kinetic analysis of mechanoradical formation during the mechanolysis of dextran and glycogen

2017 ◽  
Vol 13 ◽  
pp. 1174-1183 ◽  
Author(s):  
Naoki Doi ◽  
Yasushi Sasai ◽  
Yukinori Yamauchi ◽  
Tetsuo Adachi ◽  
Masayuki Kuzuya ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Electron Spin Resonance ◽  
Room Temperature ◽  
Particle Diameter ◽  
Helical Structure ◽  
Esr Spectra ◽  
Radical Concentration ◽  
Maximum Value ◽  
Spin Resonance ◽  
Branched Structure

A detailed electron spin resonance (ESR) analysis of mechanically induced free radicals (mechanoradicals) formation of glucose-based polysaccharides, dextran (Dx) and glycogen (Gly) was performed in comparison with amylose mechanoradicals. The ESR spectra of the samples mechanically fractured at room temperature were multicomponent. The radical concentration of Dx and Gly mechanoradicals gradually decreased during vibratory milling after reaching the maximum value. Although the molecular weight of Dx or the particle diameter of Gly steeply diminished until reaching the each maximum value of radical concentration, after that the molecular weight or the particle diameter slowly decreased. These results suggested that Dx and Gly mechanoradicals might be more unstable than amylose radicals possessing an intramolecular helical structure due to the branched structure.

scholarly journals Electron Spin Resonance Measurement with Microinductor on Chip

2011 ◽  
Vol 2011 ◽  
pp. 1-3
Author(s):  
Akio Kitagawa
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Room Temperature ◽  
Near Field ◽  
Esr Spectra ◽  
Ethanol Solution ◽  
Spin Resonance ◽  
On Chip ◽  
Processing Circuit ◽  
Probe Head

The detection of radicals on a chip is demonstrated. The proposed method is based on electron spin resonance (ESR) spectroscopy and the measurement of high-frequency impedance of the microinductor fabricated on the chip. The measurement was by using a frequency sweep of approximately 100 MHz. The ESR spectra of di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH) dropped on the microinductor which is fabricated with CMOS 350-nm technology were observed at room temperature. The volume of the DPPH ethanol solution was 2 μL, and the number of spins on the micro-inductor was estimated at about 1014. The sensitivity is not higher than that of the standard ESR spectrometers. However, the result indicates the feasibility of a near field radical sensor in which the microinductor as a probe head and ESR signal processing circuit are integrated.

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