| | 1 | Author
| S. Cannistraro, P. L. Indovina, L. Sportelli | Requires cookie* | | | Title
| Paramagnetic Species in /^-Thalassemic Sera: an ESR Study  | | | | Abstract
| Homozygous beta thalassemic sera show an electron spin resonance (ESR) signal at g ~ 6 which is not present in normal and heterozygous sera. The signal arises from high spin heme groups exhibiting a departure from tetragonal symmetry toward rhombic. Binding by a serum protein is very likely responsible for such a distortion. In contrast with other authors' findings, we report that heme-human albumin complex shows a similar rhombic distortion. The observed ESR signal at g ~ 6 is then attributed to this complex. | | | |
Reference
| Z. Naturforsch. 35c, 193—196 (1980); received November 23 1979 | | | |
Published
| 1980 | | | |
Keywords
| Heme Groups, Albumin, ^-Thalassemia, Electron Spin Resonance | | | |
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| default:Reihe_C/35/ZNC-1980-35c-0193.pdf | | | | Identifier
| ZNC-1980-35c-0193 | | | | Volume
| 35 | |
| 2 | Author
| PietroL. Indovina | Requires cookie* | | | Title
| | | | | Abstract
| We describe the appearance of a free-radical signal in the ESR spectrum of normal human serum incubated with several complement activating agents. The intensity o f this signal is dependent of dose of activating agents, time and temperature. Signals elicited by different complement activators differ in morphology and kinetics. Inhibition by treatment with EDTA and the presence o f the signal in activated C 6-deficient rabbit serum suggest that the con-vertase forming steps of complement activation (C2 to 5) could be the source of free-radical containing molecules. | | | |
Reference
| Z. Naturforsch. 35c, 844—847 (1980); received May 12/June 16 1980 | | | |
Published
| 1980 | | | |
Keywords
| Complement, Electron Spin Resonance, Free Radicals | | | |
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| default:Reihe_C/35/ZNC-1980-35c-0844_n.pdf | | | | Identifier
| ZNC-1980-35c-0844_n | | | | Volume
| 35 | |
| 4 | Author
| Robert Schupfner, Adolf Müller | Requires cookie* | | | Title
| Temperature-Dependent ESR Studies of Radical Pairs in Single Crystals of Barbituric Acid | | | | Abstract
| After irradiation o f single crystals o f barbituric acid with X-rays at 77 K different types of radical pairs are found, which are com posed o f only one type of monoradical. The properties of radical pairs o f the unpaired electrons are studied using frequency-variable ESR m ethods at various temperatures. In addition to the radical pairs A D and BC two further pairs A 'D ' and X Y were identified. M easurem ents o f the fine structure parameter D showed a linear temperature dependence in som e regions betw een 77 K and 290 K. At 240 K the radical pairs A D and A 'D ' changed reversibly into A *D * and this pair remained stable up to 290 K. A level anticrossing effect was observed with the pair A D . The exchange energy J between the singlet state and the triplet state was determ ined as —(15.1 ± 0.6) GHz at 77 K and its tem pera ture coefficient as —(3.8 ± 0.8) x 10"3K '. | | | |
Reference
| Z. Naturforsch. 44c, 849 (1989); received April 20/June 29 1989 | | | |
Published
| 1989 | | | |
Keywords
| Barbituric A cid Single Crystals Radical Pairs, Electron Spin Resonance, Level Anticrossing | | | |
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| default:Reihe_C/44/ZNC-1989-44c-0849.pdf | | | | Identifier
| ZNC-1989-44c-0849 | | | | Volume
| 44 | |
| 5 | Author
| JankoN. Herak, Günter Behrens | Requires cookie* | | | Title
| An in-situ Electron Spin Resonance Study | | | | Abstract
| ESR spectroscopy has been used to analyse the conformation of the radicals produced by the reaction of SOj with D-ribose (1), and 2-deoxy-D-ribose (6), at pH 1.3-5. From ribose three different types of radicals formed by H abstraction at C -l, C-2 and C-3 followed by a regio-selective a,ß-water elimination have been identified: the 2-deoxy-ribonolacton-2-yl (3), the 1-deoxy-pentopyranos-2-ulos-l-yl (4). and the 4-deoxy-pentopyranos-3-ulos-4-yl (2). Using deoxyribose two radicals of similar type, formed by H abstraction at C-3 and C-4 followed by water elimination, have been observed: the 2,4-dideoxy-3-ulos-4-yl (7) and the 2,3-dideoxy-4-ulos-3-yl (8). In addition, from both sugars an a-hydroxyalkyl radical has been identified based in part on the timing of their conformational motions: the ribos-3-yl (5) (the precursor of 2) and the 2-deoxy-ribos-l-yl (9), respectively. For radical 5 the rate constant k(e) for the water elimination and hence transformation into radical 2 was estimated. From the analysis of selective line broadening the frequencies of conformational changes of radicals 2 and 7 have been estimated. For 7 the frequencies of exchange of the two methylene groups were found to differ by more than 3 orders of magnitude. | | | |
Reference
| Z. Naturforsch. 41c, 1062 (1986); received January 31 1986 | | | |
Published
| 1986 | | | |
Keywords
| Free Radicals, Deoxy-D-ribose, D-Ribose, Conformational Kinetics, Electron Spin Resonance | | | |
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| default:Reihe_C/41/ZNC-1986-41c-1062.pdf | | | | Identifier
| ZNC-1986-41c-1062 | | | | Volume
| 41 | |
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