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K Möbius

Publications and source records attributed to K Möbius.

24 records · Page 2Linked to original sources
PubMed1984

Structural studies of the primary donor cation radical P(870) in reaction centers of Rhodospirillum rubrum by electron-nuclear double resonance in solution.

The light-induced cation radical of the primary electron donor, P(870) (+.), in photosynthetic reaction centers from Rhodospirillum rubrum G-9, has been investigated by electron-nuclear double resonance (ENDOR) in liquid aqueous solution. The measured hyperfine coupling constants are assigned to specific molecular positions by partial deuteration. Comparison with the bacteriochlorophyll a cation radical shows different reduction factors of the individual coupling constants deviating from the value 2.0 reported in earlier investigations in frozen solutions. The average of the coupling constants is, however, reduced by a factor very close to 2.0. EPR simulations using the ENDOR coupling constants support a dimer model for P(870) (+.) with C(2) symmetry, where the two macrocycles are close enough to form a supermolecular orbital resulting in a different distribution of the unpaired electron, compared with the monomeric bacteriochlorophyll a cation radical. Molecular orbital calculations were used to obtain structural information about this dimer.

Journal Article↗
PubMed1978

Nitrogen electron nuclear double resonance and proton triple resonance experiments on the bacteriochlorophyll cation in solution.

Electron nuclear double resonance signals of the pyrrole nitrogens of bacteriochlorophyll alpha cation in a solution of CH2Cl2/CH3OH (6:1) have been observed. The nitrogens are inequivalent: the hyperfine coupling constants were determined to be 2.36 and 3.18 MHz (0.84 and 1.14 G, respectively). Triple electron nuclear double resonance experiments have yielded the signs and values of nine proton hyperfine coupling constants. The assignment based on these data agrees well with previous work (Borg, D.C., Forman, A. & Fajer, J. (1976) J. Amer. Chem. Soc. 98, 6889-6893); in addition, two methine protons have been identified. Spin densities calculated from the hyperfine couplings are compared to reported molecular orbital calculations.

Bacteriochlorophylls↗
PubMedDate not supplied

ENDOR study of gamma-irradiated hydrated testosterone orthorhombic single crystals.

The molecular structure of free radicals formed in gamma-irradiated orthorhombic single crystals of hydrated testosterone was investigated by Electron Nuclear Double Resonance (ENDOR) spectroscopy. Only one kind of radical was observed, which is formed by addition of hydrogen atom to oxygen atom O(3). We observed interaction of the unpaired electron, which is delocalized on the carbons C(3), C(4) and C(5), with one alpha-proton in position 4 and with four unequivalent beta-protons connected with the carbon atoms C(2) and C(6). The matrices of the hyperfine couplings and the g-factor of the radical are given.

Crystallization↗