Desulfothermobacter acidiphilus gen. nov., sp. nov., a thermoacidophilic sulfate-reducing bacterium isolated from a terrestrial hot spring.

An anaerobic sulfate-reducing micro-organism, strain 3408-1T, was isolated from a terrestrial hot spring in Kamchatka peninsula (Russia). The cells were spore-forming rods with a Gram-positive type of cell wall. The new isolate was a moderately thermoacidophilic anaerobe able to grow either by sulfate or thiosulfate respiration with H2 or formate as substrates, or by fermenting yeast extract, maltose, sucrose, glucose and pyruvate. The fermentation products were acetate, CO2 and H2. The pH range for growth was 2.9-6.5, with an optimum at 4.5. The temperature range for growth was 42-70 °C, with an optimum at 55 °C. The G+C content of DNA was 58 mol%. Phylogenetic analysis of the 16S rRNA gene showed that strain 3408-1T belongs to the family Thermoanaerobacteraceae, order Thermoanaerobacterales and was distantly related to the species of the genus Ammonifex(93-94 % sequence similarity). On the basis of physiological properties and results of phylogenetic analysis, strain 3408-1T is considered to represent a novel species of a new genus, for which the name Desulfothermobacter acidiphilus gen. nov., sp. nov. is proposed. The type strain is 3408-1T (=DSM 105356T=VKM B-3183T).

Hemoglobin dynamics in rat erythrocytes investigated by Mössbauer spectroscopy.

Rats have been enriched in 57Fe and erythrocytes were isolated from the blood. Mössbauer absorption spectroscopy on the hemoglobin of these erythrocytes has shown rather similar dynamics as found earlier in crystals of myoglobin, in frozen solutions of human hemoglobin and in a number of other proteins. The results strongly indicate that the motion of the heme and presumably some part of the F-helix is mainly influenced by the average viscosity of the sample determined by a network of hydrogen bridges and other weak interactions. Extrapolations of Mössbauer results from protein crystals to proteins in their physiological surroundings seem to be suitable for heme proteins.

[Role of conformational sub-states on the reaction capacity of protein molecules]. / Rol'konformatsionnykh podsostoianii v reaktsionnoi sposobnosti belkovykh molekul.

A review of the recent data on protein dynamics (mainly myoglobin) by X-ray technique, Mössbauer spectroscopy and Rayleigh scattering of Mössbauer radiation is given. The connection between dynamical and functional properties of biological systems are discussed.

[Mössbauer spectroscopy of intramolecular mobility in chromatophores from Rhodopseudomonas spheroides]. / Issledovanie vnutrimolekuliarnoi podvizhnosti khromatoforov iz Rhodopseudomonas sphaeroides metodom Messbauérovskoi spektroskopii.

Mobility of the Mössbauer label attached to the membrane proteins and the Mössbauer probe embedded into the lipid matrix of the bacterial chromatophores were studied. Positive correlation was established between the dynamic properties of hydrophobic compartments in the chromatophores and functional electron--transport activity at the level of quinone cofactors associated with the photosynthetic reaction centres.

Electron tunneling process and the segment mobility of macromolecules.

New experimental data [Berg, A. I., Noks, P. P., Kononenko, A. A., Frolov, E. N., Khrymova, I. N., Rubin A. B., Likhtenstein, G. I., Goldanskii, V. I., Parak, F., Bukl, M. & Mössbauer, R. (1979) Mol. Biol. (USSR) 13, 81-89; Berg, A. I., Noks, P. P., Kononenko, A. A., Frolov, E. N., Uspenskaya, N. Y., Khrymova, I. N., Rubin, A. B., Likhtenstein, G. I. & Hideg, K. (1979) Mol. Biol (USSR) 13, 469-477] provide evidence that the electron tunneling process is connected to a special type of conformational transition (segmental transition) protein macromolecules in photosynthetic membranes. This problem is investigated with a simple mechanical model. It is shown that the segmental degree of freedom can play the role of the strongly interacting accepting mode for the electron tunneling process. The temperature dependences of the electron tunneling rate and the recoilless gamma-ray absorption of membrane-bound 57Fe, as an indicator of the intramolecular mobility, are calculated. The problem of energy storage in proteins is also discussed.

[Spin label study of the temperature stability of plant fibers]. / Issledovanie temperaturnoi stabil'nosti rastitel'nykh volokon metodom spinovykh metok.

Temperature relationship of rotation diffusion parameters of radical connected to different varieties of cotton filament, isolated from normal and with affected cotton was studied. It has been found that structural transitions accompanied with a markable increase of radical rotation diffusion in all the samples studied, proceed at definite temperatures. For filament samples from wilt-affected plants temperatures at which structural transitions proceed are higher as compared to the filaments taken from normal plants. This phenomenon point to higher micro rigidity of wilt-affected plants.

[Effect of temperature and degree of hydration on the mobility of spin labels in surface layers of proteins]. / Vliianie temperatury i stepeni gidratatsii na podvizhnost' spinovykh metok v poverkhnostnykh sloiakh belkov.

The mobility of separate sites of the water-protein matrix depending on temperature and degree of hydration has been investigated by means of spin labels covalently attached to surface layers of proteins (alpha-chymotrypsin and human serum albumin) and also by a spin probe in a hydrophobic "pocket" of human serum albumin. The results obtained are compared with the data on the mobility of gamma-resonance labels (57Fe) firmly bound with the protein matrix in the same samples. At certain temperature and degree of hydration both spin and gamma-resonance label show an increase in mobility. With the degree of hydration increasing one may observe a simultaneous increase in energy and in entropy of activation: rotatory diffusion of spin labels, i. e., a compensation effect takes place which confirms the concept expressed earlier that cooperation of water-protein interactions is the main reason of CEF. It should be noted that at P/PS greater than 0.8 the values of delta E =7 divided by 10 kcal/mole, and delta S not equal to = 9 divided by 11 e. e. are specific to glycerol-like systems, i. e., under these conditions (P/Ps greater than 0.8) the water-protein layer has glycerol-like properties.

[Study of the dynamics of water-protein systems by the technic of gamma-resonance spectroscopy]. / Issledovanie dinamiki vodno-belkovykh sistem metodom gamma-rezonansnoi spektroskopii.

The possibility of using gamma resonance spectroscopy (GRS) for studying the dynamics of water-protein systems is shown in the present work. The experiments were carried out on an albumin-water system. The results obtained are compared with those obtained by the spin label method under the same conditions. The different behaviour of Fe ions which are firmly- and weakly-related with the protein matrix allows to separate the mobility of the whole protein macromolecule and also the mobility of its subunits.

[Conformational mobility and functional activity of photosynthetic reaction centers of Rhodopseudomonas sphaeroides]. / Konformatsionnaia podvizhnost' i funktsional'naia aktivnost' fotosinteticheskikh reaktsionnykh tsentrov iz Rhodopseudomonas sphaeroides.

In pigment-protein complexes of photosynthetic reaction centres (RC's), extracted from chromatophore membranes of Rps. sphaeroides with sodium dodecylsulphate, functional activity and intramolecular mobility were studied as a function of temperature and hydration by use of the technique of optical absorbance and ESR spectroscopy. Over the studied temperature range from +20 to -120 degrees C and at a relative humidity (P/Ps) from 0.9 to 0.1, there observed a close interrelationship between reversible kinetic changes of direct and backward redox-reactions of the photo-reduced endogeneous acceptor of quinone nature and the effective parameter of the correlation time of the rotational diffusion of the hydrophobic spin probe as well as of spin labels chemically bound to SH- and COOH-groups of amino acid residues of the RC's protein. The findings support the view that the conformational dynamics in the RC controls the effectiveness of the primary processes of stabilization of photochemically separated charges.

[Conformational regulation of functional activity of photosynthetic membranes of purple bacteria]. / Kanformatsionnei regulirovanie funktsional'noi aktivnosti v fotosinteticheskikh membranakh purpurnykh bakterii.

In reaction centres of photosynthetic membranes of R, rubrum the efficiency of redox interactions of the photoreduced primary electron acceptor with secondary acceptors and photooxidized bacteriochlorophyll has a marked and reversible dependence on temperature over the range from -20 degrees to -80 degrees. Similar temperature dependences were observed for correlation times of the rotational diffusion of a spin probe bound to the hydrophobic region of the membrane and of a spin label bound to SH-groups of the protein constituent of the membrane, as well as for characteristics of resonance absorption of the Mössbauer probe (57Fe), embedded in the membrane by biosynthesis. Using the same indicators of intramolecular mobility, a correlation has been observed between photoactivity and structure of the membrane in experiments involving hydratation changes of samples. The data suggest the existence of a close interrelationship between the conformational mobility of the constituents of the photosynthetic membrane and their specific reaction capacity.