[Linear dichroism of pigments associated with spherical chromatophores. Models of orientation in polyacrylamide gels]. / Lineinyi dikhroizm pigmentov sfericheskikh khromatoforov. Model' orientatsii v poliakrilamidnom gele.

Linear dichroism and orientation of pigments in chromatophores of photosynthetic bacteria Chromatium minutissimum and Rhodospirillum rubrum using a novel method of orientation in polyacrylamide gel was studied. A model is proposed for orientation of spherical membranes of chromatophores or other similar vesicules. The value of linear dichroism is derived for known deformation of the gel and a certain angle between the transition dipole and a unit vector perpendicular to the membrane plane. The analysis of linear dichroism spectra permits calculation of angles between the normal to the membrane and the transition dipoles in Chr. minutissimum 65 degrees +/- 1.5 degrees (890 nm absorption band), 63 degrees +/- 1 degree (860 nm), 63 degrees +/- 1 degree (800 nm), 45.5 degrees +/- 1 degree (590 nm), 50.5 degrees +/- 0.5 degree (450--550 nm) and in Rsp. rubrum: 71 degrees +/- 1.5 degree (890 nm), 66.5 degrees +/- 1 degree (870 nm), 69 degrees +/- 1.5 degree (800 nm), 37 degrees +/- 0.5 degree (590 nm), 49.5 degrees +/- 0.5 degree (450--550 nm). The 860 nm band shift to shorter wave-lengths observed in Chr. minutissimum chromatophores treated with 0.01 M potassium ferricyanide is not related to reorientation of transition dipoles, but rather to certain changes of lipid-protein environment.

[Molecular organization of the long-wave complexes of purple photosynthesizing bacteria. Effect of pronase on the B890 complex of Chromatium minutissium and Rhodopseudomonas palustris]. / Molekuliarnaia organizatsiia dlinnovolnovykh kompleksov purpurnykh fotosinteziruiushchikh bakterii. Issledovanie deistviia pronazy na kompleksy B890 Chromatium minutissimum i Rhodopseudomonas palustris.

The pronase action on the long-wave complexes B890 from two different purple bacteria has been investigated. Differences in the kinetics of decrease of the reaction center photochemical activity of electron-donor activity of cytochromes and of destruction of Bx890 (875) forms have been discovered. Different rates of the proteolysis of RC proteins were revealed by SDS-gel-electrophoresis. The heavy protein of RC was the first to degrade. The photochemical transformations deltaA890(875) in B890 complexes was observed during formation of peptides with molecular weight about 17 000 from two other RC proteins. On the basis of obtained data the model of molecular organization of B890 complexes from purple bacteria is discussed.

[Analysis of the linear dichroism of reaction centers oriented in polyacrylamide gel]. / Analiz lineinogo dikhroizma reaktsionnykh tsentrov, orientirovannykh v poliakrilamidnom gele.

A model for orientation of rigid disc-shaped and rod-shaped macromolecules in polymer is analysed. Analytical expressions are given for the dependence of linear dichroism value on the angle between the transition dipole vector and the axis of the macromolecules, for certain deformation of the sample. The reaction centers from Rhodopseudomonas sphaeroides R-26 are oriented as rod-shaped particles. The angles between the long axis of the reaction center and transition dipoles for bacteriochlorophyll 31.8 +/- 2,4 degrees (870 nm), 42,3 +/- 0.9 degrees (796 nm), 68.0 +/- 0.6 degrees (600 nm) and for bacteriopheophytin 76.5 +/- 1.9 degrees (760 nm), 39.8 +/- 1.5 degrees (540 nm) are determined from absorption spectra.

[Molecular organization of bacteriochlorophyll in the light-converging B850 complex of purple bacteria]. / Molekuliarnaia organizatsiia bakteriokhlorofilla v svetosobiraiushchem komplekse B850 purpurnykg bakterii.

The light-harvesting bacteriochlorophyll-protein complex B850 has been isolated from two species of purple bacteria, Rhodopseudomonas palustris and Chromatium minutissimum. Absorption and fluorescence spectra at 20 degrees and--196 degrees C of this complex were registered. Second derivatives of the absorption spectra, Stepanov's relation and computer curve analyses in terms of asymmetrical Gaussian components show that absorption spectra consist of five and fluorescence spectra--of three components. These components were analysed in terms of exciton interaction among bacteriochlorophyll molecules. Data obtained were used for building-up of the molecular model of the complex.

[EPR study of redox titration of Chromatium minutissimum chromatophores]. / Izuchenie metodom EPR okislitel'no-vosstanovitel'nogo titrovaniia khromatoforov Chromatium minutissimum.

Redox titration of chromatophores through the region +300 +570 mV at room temperature results in generation of two dark ESR signals, a well-known reaction center signal and a new narrow line. This line is characterized by deltaH pp = 4.2 Oe, g-factor about that of RC and a Lorentzian shape. It is insensitive to illumination. The determination of an RC signal midpoint potential is affected by the presence of the narrow line. Taking into account the superposition of the two ESR signals it was measured to be +(486+/-+/-18)mV.

[Role of bacteriochlorophyll in stabilization of the structure of the near-central and peripheral light-harvesting complexes from purple photosynthetic bacteria].

Pheophytinization of bacteriochlorophyll (BChl) at low pH was investigated in the core (LH1) and peripheral (LH2) light-harvesting complexes, as well as in the ensemble of the reaction center (RC) with the LH1 complex. The stages in disintegration of the native BChl forms in the LH1 complex and in its ensemble with RC were revealed. They were observed as emergence of the absorption band of monomeric BChl and an increase in its intensity, followed by its transformation into the band of monomeric bacteriopheophytin (BPh) and then into the band of aggregated BPh. Unlike the LH1 complex, in the case of the LH2 complex monomeric BChl was never detected as an intermediate product. While the spectra revealed formation of monomeric BPh, its accumulation did not occur, since its aggregation is very rapid compared to that in the LH1 complex and in the RC-LH1 ensemble. PAG electrophoresis revealed that pheophytinization of BChl in the LH2 complex was accompanied by disruption of the stable cylindrical structure of this complex with emergence of characteristic fragments consisting of α and ß peptides and bearing monomeric BPh, as well as of the α peptide aggregates bearing BPh aggregates. Unlike the LH2 complex, BChl pheophytinization in the LH1 complex did not result in its fragmentation. This is an indication of different types of structural stabilization in the LH1 and LH2 complexes. In the LH2 complex, coordination of bacteriochlorophyll Mg2+ by conservative histidine residues of the α and ß polypeptides is the main factor responsible for the maintenance of its cylindrical structure. Stability of the LH1 complex is probably based primarily on the highly specific hydrophobic interactions between the surfaces of individual polypeptide chains, since the presence of hydrogen bonds results in autonomy of each αß3BChl2 subunit, rather than in stabilization of the LH1 complex as a whole.

[Distribution of bacteriochlorophyll between the pigment-protein complexes of the sulfur photosynthesizing bacterium Allochromatium minutissimum depending on light intensity at different temperatures].

Variation of the distribution of bacteriochlorophyll a (BChl a) between external antenna (LH2) and core complexes (LHl + RC) of the photosynthetic membrane of the sulfur bacterium Allochromatium minutissimum was studied at light intensities of 5 and 90 Wt/m2 in the temperature range of 12-43 degrees C. The increase of light intensity was shown to result in a 1.5- to 2-times increase of a photosynthetic unit (PSU). PSU sizes pass through a maximum depending on growth temperature, and the increase of light intensity (5 and 90 Wt/m2) results in a shift of the maximal PSU size to higher temperatures (15 and 20 degrees C, respectively). In the narrow temperature interval of approximately 14-17 degrees C, the ratio of light intensity to PSU size is typical of phototrophs: lower light intensity corresponds to larger PSU size. The pattern of PSU size change depending on light intensity was shown to differ at extreme growth temperatures (12 degrees C and over 35 degrees C). The comparison of Alc. minutissimum PSU size with the data on Rhodobacter capsulatus and Rhodopseudomonas palustris by measuring the effective optical absorption cross-section for the reaction of photoinhibition of respiration shows a two to four times greater size of light-harvesting antenna for Alc. minutissimum, which seems to correspond to the maximum possible limit for purple bacteria.

[Assembly of LH2 light-harvesting complexes in Rhodopseudomonas palustris cells illuminated by blue and red light].

We investigated the formation of the B800-850 complex in cells of the bacterium Rhodopseudomonas palustris AB illuminated by red and blue light under anaerobic growth conditions. Under red illumination, the B800-850 complex was assembled with a reduced absorption band at 850 nm. The results of re-electrophoresis of the B800-850 complex and oxidation in the presence of potassium iridate suggest its heterogeneity. It may be a mixture of two complexes (B800 and B800-850). The B800-850 complex lacks the capacity for conformational transitions if assembled under blue illumination. Accordingly, the light-harvesting complex assembled in the blue light contains polypeptides that are not synthesized under normal conditions or at increased or decreased light intensities. The mechanism of regulation of the synthesis of the polypeptides of light-harvesting B800-850 complex and its dependence on the spectral composition of the light is discussed.

[Isolation and characterization of pigment-protein complexes from green serobacteria Chlorobium limicola forma thiosulfatophilum]. / Vydelenie i kharakteristika pigment-belkovykh kompleksov iz zelenoi serobakterii Chlorobium limicola forma pigment-belkovykh kompleksov iz zelenoi serobakterii Chlorobium limicola forma thiosulfatornilum.

A subchromatophore fraction containing the reaction center P-840 was isolated from the chromatophores of green serobacteria Chlorobium limicola forma thiosulfatophilum by ultracentrifugation and its protein composition was characterized. After treatment of the chromatophores by Triton X-100 and subsequent polyacrylamide gel electrophoresis two pigment-protein complex containing bacterioviridin. The proteins of the pigment-protein complex containing bacterioviridin. The proteins of the pigment-protein complexes were obtained. The first complex contained mainly bacteriochlorophyll alpha with bacterioviridin contaminations and the second one-only bacterioviridin. The low-temperature absorption spectrum of the bacteriochlorophyll alpha-containing pigment-protein complex is identical to the absorption spectrum of a water-soluble pigment-protein complex isolated and characterized by Olson and contains proteins with molecular weights of 34.800, 33.100, 27.500 and 23.200. A protein with molecular weight of 32.700 was found in the pigment-protein complexes were compared to the proteins of the photochemically active subchromatophore fraction and chromatophores.

[Comparative study of B890 pigment-lipoprotein complexes from sulfur (Chromatium minutissimum) and non-sulfur (Rhodopseudomonas palustris) purple photosynthesizing bacteria]. / Sravnitel'noe issledovanie pigment-lipoproteinovykh kompleksov B890 is sernykh (Chromatium minutissimum) i nesernyky (Rhodopseudomonas palustris) purpurnykh fotosinteziruiushchikh bakterii.

Pigment-lipoprotein B890 complexes containing reaction center and "light-focusing" bacteriochlorophyll a were isolated from photosynthetic membranes of sulfur (Chromatium minutissimum) and non-sulfur (Rhodopseudomonas palustris) purple bacteria after the treatment with Triton X-100. The molecular weights of complexes were evaluated using several methods (200 000-300 000). By means of electron microscopy the sizes of complexes were found to be about 80 A. On the air-water interface hexagonal packing of complexes was observed. The chemical compositions of complexes are very similar except bacteriochlorophyll a whose specific content is somewhat higher in Chromatium minutissimum. The protein composition of complexes was studied and the molecular weights of proteins were estimated by SDS-gel electrophoresis. The results obtained show significant similarities in molecular organization of B890 complexes isolated from sulfur (Chromatium minutissimum) and non-sulfur (Rhodopseudomonas palustris) purple bacteria.

[Comparative study of light-harvesting complexes of purple photosynthetic bacteria Chromatium minutissimum and Rhodopseudomonas palustris]. / Sravnitel'noe izuchenie svetosobiraiushchikh kompleksov purpurnykh fotosinteziruiushchikh bakterii Chromatium minutissimum i Rhodopseudomonas palustris.

Light-harvesting pigment-lipoprotein complexes from sulfur (Chromatium minutissimum) and non-sulfur (Rhodopseudomonas palustris) purple bacteria are isolated and comparatively studied. Electron microscopy was used for determination of the complex size, different methods were employed to estimate their molecular weights and chemical composition. Two small proteins are found in each complex, their molecular weight, molar ratio and their content per complex being studied. Amino acid composition and N-terminal amino acids are determined for both proteins of light-harvesting complex from Chromatium minutissimum. Some common characteristics of the molecular organization of light-harvesting complexes in purple bacteria are discussed.