[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.

[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.

[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.