Radical Generation upon γ-Irradiation of Two Amorphous and Two Crystalline Forms of Water at 77 K

Bednarek, Janusz; Płonka, Andrzej; Hallbrucker, Andreas; Mayer, Erwin

doi:10.1021/jp9826571

Cited by 18 publications

(27 citation statements)

References 37 publications

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“…As the system is closed, we cannot absolutely determine whether the sample has cooled amorphously or whether crystalline ice has formed. However, the EPR signal is largely independent of this (Bednarek et al, 1998), so unhke during crystallographic studies, the type of ice formed does not impact on the measurements.…”

Section: Irradiations and Eprmentioning

confidence: 99%

“…While the type of ice (amorphous, hexagonal or cubic) does not greatly influence the free-radical signal (Johnson & Moulton, 1978;Bednarek et al, 1998), the behavior of ice at 4K and at 100 K might do so. Johnson & Moulton (1978) noted that the temperature at which ice is irradiated has a significant effect on the free-radical yield of both OH* and HO' radicals.…”

Section: Residue Solvent Accessibility (A )mentioning

confidence: 99%

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Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies

Sutton

Black

Mercer

et al. 2013

Acta Crystallogr D Biol Crystallogr

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Section: Irradiations and Eprmentioning

confidence: 99%

Section: Residue Solvent Accessibility (A )mentioning

confidence: 99%

Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies

Sutton

Black

Mercer

et al. 2013

Acta Crystallogr D Biol Crystallogr

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“…7 It is relevant to add that HO 2 · radicals were also observed, after low-dose irradiation, in vapor-deposited amorphous solid water (prepared without ultrasonic treatment), which like HGW is rich in L-type defect sites. 8 As seen from Figure 1b, the significant fraction of crystalline ice in HGW made with a pneumatic nebulizer does not seem to have an effect on the HO 2 · yield. However, we previously found that HGW samples made by hyperquenching large droplets (e25 µM diameter) contain mainly cubic ice as crystalline component (cf., ref 11 and Figure 3b therein) and that this type of γ-irradiated cubic ice has relative OH · /HO 2 · yields similar to those of HGW (cf., Figure 4 in ref 10).…”

Section: Resultsmentioning

confidence: 77%

“…The latter finding had been rationalized by the presence of defects in cubic ice. 8 Figure 2 presents ESR spectra recorded at 77 K for the dGMP/HGW system immediately after irradiation, and after successive annealing of the sample at higher temperatures. The initial spectrum (nonannealed sample) is distinctly different from that obtained for neat HGW, indicating the presence of solutederived radicals in addition to OH · and HO 2 · radicals.…”

Section: Resultsmentioning

confidence: 99%

Radicals Produced by γ-Irradiation of Hyperquenched Glassy Water Containing 2′-Deoxyguanosine-5′-monophosphate

et al. 2008

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Hyperquenched glassy water (HGW) has been suggested as the best model for liquid water, to be used in low-temperature studies of indirect radiation effects on dissolved biomolecules (Bednarek et al. J. Am. Chem. Soc. 1996, 118, 9387). In the present work, these effects are examined by X-band electron spin resonance spectroscopy (ESR) in gamma-irradiated HGW matrix containing 2'-deoxyguanosine-5'-monophosphate. Analysis of the complex ESR spectra indicates that, in addition to OH(*) and HO2(*) radicals generated by water radiolysis, three species are trapped at 77 K:(i) G(C8)H(*) radical, the H-adduct to the double bond at C8; (ii) G(- *) radical anion, the product of electron scavenging by the aromatic ring of the base; and (iii) dR(-H)(*) radicals formed by H abstraction from the sugar moiety, predominantly at the C'5 position. We discuss the yields of the radicals, their thermal stability and transformations, as well as the effect of photobleaching. This study confirms our earlier suggestion that in HGW the H atom addition/abstraction products are created at 77 K in competition with HO2(*) radicals, in a concerted process following ionization of water molecule at L-type defect sites of the H-bonded matrix. The lack of OH(*) reactivity toward the solute suggests that the H-bonded structure in HGW is much more effective in recombining OH(*) radicals than that of aqueous glasses obtained from highly concentrated electrolyte solutions. Furthermore, complementary experiments for the neat matrix have provided evidence that HO2(*) radicals are not the product of H atom reaction with molecular oxygen, possibly generated by ultrasounds used in the process of sample preparation.

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“…The formation of HO 2 is attributed to the presence of shallow proton traps or Bjerrum-like L-defects. 76 …”

Section: Primary Eventsmentioning

confidence: 99%

7 Radiation chemistry

Belloni

Delcourt

Houée-Levin⊥

et al. 2000

Annu. Rep. Prog. Chem., Sect. C

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We try in this review to survey advances in all the aspects of Radiation Chemistry (the effects of high energy or ionizing radiation), both basic and applied, made during the period 1995^1999, after the last report issued at the end of 1994. 1 Classically, two main classes of studies are relevant. The ¢rst one includes the primary phenomena induced by the interaction of high-energy radiation with a chemical system. The way the energy is spatially deposited is indeed highly nonhomogeneous and depends on the type of radiation considered. Mutual reactions between the primary species produced also depend on their initial spatial distribution, and therefore on the energy absorption pattern. The kinetic aspects derive directly from the initial events following radiation absorption and thus, when observed at times as short as possible, give useful information on the early energy distribution for each of the radiation types, X-and g-photons, electrons and heavy particles, and, on the in£uence of their intensity and energy per particle.The second class of studies utilizes the background knowledge of radiation chemistry to generate and then to observe the fate of chemical transient species known to be involved in very important chemical or biochemical processes. Numerous data, such as the nature of reaction products, the absolute rate constants, the sequence of elementary reactions constituting a mechanism, and the thermodynamic and spectroscopic properties of short-lived species have been attained. This kind of study of transients and reaction mechanisms, which can be approached only by pulse techniques (essentially pulse radiolysis or laser photolysis, each with its speci¢c advantages), constitutes the new ¢eld of fast to ultrafast chemistry. It concerns extended domains of physical, organic, inorganic, and bio-chemistry. Moreover, the understanding of mechanisms is quite helpful in suggesting new ways of synthesis or degradation induced by irradiation and is now extensively used in developing various speci¢c processes in applied chemistry. The number of studies on the chemical mechanisms and in applied radiation chemistry constitutes an increased fraction of the total publications in radiation chemistry, which we estimate to be around 4000 over the period considered (almost constant compared to the preceding 5-year

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Radical Generation upon γ-Irradiation of Two Amorphous and Two Crystalline Forms of Water at 77 K

Cited by 18 publications

References 37 publications

Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies

Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies

Radicals Produced by γ-Irradiation of Hyperquenched Glassy Water Containing 2′-Deoxyguanosine-5′-monophosphate

7 Radiation chemistry

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