| 1 | Author
| Heinz Rupp, K., Jozef Verplaetse, Rene Lontie | Requires cookie* | | Title
| Binuclear Copper Electron Paramagnetic Resonance Signals of a-Methemocyanin of Helix pomatia  | | | Abstract
| The binuclear electron paramagnetic resonance signals o f a-methemocyanin o f Helix pomatia were investigated at liquid helium temperatures. These signals were completely eliminated by the addition of fluoride and enhanced in the presence o f chloride, which did not alter the saturation behavior. The triplet nature of the signal at g = 4.59 was confirmed by the low power-saturation. The addition of nitrite at pH 5.0 and 0° C yielded slowly and reversibly a seven-line half-field signal. On lowering the temperature the intensity of the triplet signals increased to the lowest tem perature reached 4.2 K, excluding a strong exchange coupling. | | |
Reference
| Z. Naturforsch. 35c, 188—192 (1980); received September 18/November 17 1979 | | |
Published
| 1980 | | |
Keywords
| Copper, Electron Paramagnetic Resonance, Hemocyanin, Microwave Power Saturation | | |
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| default:Reihe_C/35/ZNC-1980-35c-0188.pdf | | | Identifier
| ZNC-1980-35c-0188 | | | Volume
| 35 | |
2 | Author
| R. Om, G., EligiuszS. Erafin, JanuszM. Azur | Requires cookie* | | Title
| The Kinetics of the Reaction of Thiocyanate and Nitrite Ions with Orconectes limosus Oxyhemocyanin  | | | Abstract
| The time course of the reaction of oxyhemocyanin from the arthropod Orconectes limosus with SCN" and N 0 2 " was investigated. After addition of one of these anions to oxyhemocyanin solu tion an exponential decay of A 340 was found, indicating a removal of oxygen from the active site. The order of reaction with respect to ligand was about 3 for thiocyanate and about 1 for nitrite. On this basis, a possible arrangement of ligands in the active site has been proposed. The final product of reaction with SCN" yielded a mononuclear copper EPR spectrum while the reaction product with N 07 gave a characteristic spectrum of two coupled Cu2+ ions. It was possible to remove the ligands from the active site by dialysis. The reaction patterns showed distinct changes in a narrow pH range, 5.3—6.5. A possible effect of structural alterations of the protein moiety on the course of the reaction of oxyhemocyanin with ligands is suggested. | | |
Reference
| Z. Naturforsch. 40c, 677—681 (1985); received February 4 1985 | | |
Published
| 1985 | | |
Keywords
| Hemocyanin, Reaction Kinetics, Copper, Electron Paramagnetic Resonance | | |
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| default:Reihe_C/40/ZNC-1985-40c-0677.pdf | | | Identifier
| ZNC-1985-40c-0677 | | | Volume
| 40 | |
4 | Author
| C. B. Azzoni, M. C. Mozzati, A. Paleari, V. Massarotti, D. Capsoni, M. Bini | Requires cookie* | | Title
| Magnetic Order in Li-Mn Spinels  | | | Abstract
| Magnetic measurements were carried out on different samples of Lithium-Manganese spinel LiMn 2 0 4 , great care having been taken to avoid the presence of spurious magnetic phases, such as Mn 3 0 4 . Sus-ceptibility data, showing deviations from paramagnetic behaviour at about 40 K, were analyzed in terms of local magnetic interactions, taking into account the structural and transport properties of these com-pounds. The magnetic response of pure and stoichiometric samples suggests that the onset of a long-range magnetic ordering is hindered by the topological frustration of the antiferromagnetic octahedral sublattice of the spinel. | | |
Reference
| Z. Naturforsch. 53a, 693—698 (1998); received April 25 1998 | | |
Published
| 1998 | | |
Keywords
| Magnetic Susceptibility, Electron Paramagnetic Resonance, Lithium Manganese Oxides, Lithium Manganese Spinel | | |
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| default:Reihe_A/53/ZNA-1998-53a-0693.pdf | | | Identifier
| ZNA-1998-53a-0693 | | | Volume
| 53 | |
5 | Author
| C. B. Azzoni, M. C. Mozzati, A. Paleari, V. Massarotti, M. Bini, D. Capsoni | Requires cookie* | | Title
| Evidence of a Cationic Substitution Domain in Lithium-Manganese Spinels  | | | Abstract
| Magnetic susceptibility measurements and electron paramagnetic resonance spectra of samples prepared from the reactive system Mn0/Li 2 C0 3 with different starting Li cationic fraction x are analyzed, taking into account the structural and compositional information provided by x-ray diffrac-tion. Parent phases, as Mn 2 0 3 , Mn 3 0 4 and Li 2 Mn0 3 , arise together with the lithium-manganese spinel as a result of Li-deficiency or Li-excess with respect to the x = 0.33 composition pertinent to the stoichiometric LiMn 2 0 4 spinel. The data show that the spinel phase can sustain a partial Li-Mn substitution in the cation sites, according to compositional models described, for x > 0.33, by Lii +y Mnit 3y Mnf+ 2y 0 4 (Li-rich spinel) and, for x < 0.33, by Lii_| J/ |Mn^|Mn^| y |Mnfi| I/ |0 4 (Li-poor spinel). Paramagnetic resonance data of the Li-poor spinel phase are analyzed to discuss the possible oxidation state of Mn in the tetrahedral site. | | |
Reference
| Z. Naturforsch. 53a, 771—778 (1998); received June 22 1998 | | |
Published
| 1998 | | |
Keywords
| Stoichiometric LiMn 2 0 4 Spinel Phase, Magnetic Susceptibility, Electron Paramagnetic Resonance | | |
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| default:Reihe_A/53/ZNA-1998-53a-0771.pdf | | | Identifier
| ZNA-1998-53a-0771 | | | Volume
| 53 | |
6 | Author
| L. Kovács3, U. Hegdeb, S. Padhyeb, G. Bernät3, S. Demeter3 | Requires cookie* | | Title
| Effects of Potassium-(picrate)-(18-crown-6) on the Photosynthetic Electron Transport  | | | Abstract
| The effects of potassium-(picrate)-(18-crown-6) on the electron transport of photosystem II was investigated in isolated pea thylakoids. Low concentrations of the compound inhibited the fast decay of fluorescence yield associated with electron transfer between the primary (Q a) and secondary (Q b) quinone electron acceptor and increased the intermediary level of fluorescence to the Fmax level. The decay half-time of fluorescence yield measured in the presence of D C M U (S2Q A' charge recombination) decreased from about 1.8 s to about 0.3 s in thylakoids treated with potassium-(picrate)-(18-crown-6). W hile the inhibition of electron transport by D C M U gave rise to the appearance of a thermoluminescence band at about + 10°C (S2Q A~charge recombination) addition of potassium-(picrate)-(18-crown-6) resulted in a thermoluminescence band at about -10°C. Increasing concentrations of potassium-(picrate)-(18-crown-6) diminished the fluorescence yield and the -10°C TL band and abolished the Signal II S and Signal I I f E P R signals of the tyrosine-D and tyrosine-Z electron donors, respec tively. The phenolic-type inhibitor, potassium picrate had the same effect on thermolumines cence and on the tyrosine E P R signals. It is concluded that potassium-(picrate)-(18-crown-6) is a phenolic type inhibitor owing to its picrate constituent. A t low concentrations picrate and potassium-(picrate)-18-crown) not only block the electron transport between Q A and O b but they probably decrease the midpoint redox potential of Q A, as well. A t high concen trations they also inhibit the light-induced oxidation of the tyrosine-D and tyrosine-Z donors. | | |
Reference
| Z. Naturforsch. 51c, 539—547 (1996); received December 22 1995/ | | |
Published
| 1996 | | |
Keywords
| Phenolic Inhibitors, Photosynthesis, Photosystem II, Thermoluminescence, Electron Paramagnetic Resonance | | |
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| default:Reihe_C/51/ZNC-1996-51c-0539.pdf | | | Identifier
| ZNC-1996-51c-0539 | | | Volume
| 51 | |
7 | Author
| A. B. Vassilikou-Dova, K. Eftaxias | Requires cookie* | | Title
|  | | | Abstract
| In clear, blue, transparent bipyramidal crystals of the rare mineral benitoite, BaTiSi30 9, para magnetic defects have been investigated by electron paramagnetic resonance at room temperature and 9.43 GHz. They are attributed to Sn3+ and Fe3 + . A pair of satellites recorded for a wide angular rage around B0 || c (~40°) and a relative intensity of ~ 13% to the central signal is most likely due to hyperfine interaction with 117Sn and 119Sn isotopes. Attempts to bleach the colour of the crystal were unsuccessful. | | |
Reference
| Z. Naturforsch. 46a, 579—582 (1991); received February 18 1991 | | |
Published
| 1991 | | |
Keywords
| Electron paramagnetic resonance, Radiation defects, Minerals, Sn3 +, Fe3 + | | |
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| default:Reihe_A/46/ZNA-1991-46a-0579.pdf | | | Identifier
| ZNA-1991-46a-0579 | | | Volume
| 46 | |
9 | Author
| J. Paul, E. V. Goldammer, H. R. Wenzel | Requires cookie* | | Title
| Pressure Induced Structural Fluctuations in Hemoglobin, Studied by EPR-Spectroscopy  | | | Abstract
| A quartz based cavity for pressure dependent EPR measurements on liquid samples allowing pressures up to 0.6GPa was constructed. First investigations with this setup were done on spin labeled horse hemoglobin derivatives both in ferric and ferrous state of oxidation. The second derivative EPR spectra show changes of the label's mobility, which are not correlated with spin state changes of the Fe-porphyrin complex, but which point out structural fluctuations inside the globin protein matrices. | | |
Reference
| Z. Naturforsch. 43c, 162—166 (1988); received December 22 1987 | | |
Published
| 1988 | | |
Keywords
| High-Pressure, Electron Paramagnetic Resonance, Second Harmonic Detection, Liquid Systems, Hemo-Proteins, Structural Fluctuation, Ligand Binding | | |
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| default:Reihe_C/43/ZNC-1988-43c-0162.pdf | | | Identifier
| ZNC-1988-43c-0162 | | | Volume
| 43 | |
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