[Polarization of prompt and delayed fluorescence of photosystem II]. / Poliarizatsiia bystroi i zamedlennoi fluorestsentsii fotosistemy II.

Prompt and delayed fluorescence polarization of the oriented samples of synchronous. Chlorella vulgaris culture is investigated. Two main components with different polarization are revealed in the prompt and delayed fluorescence, however its ratio depends on the emission nature. The delayed fluorescence polarization ratio indicates that the reaction center pigment of PS-II dipole transition moment is in the photosynthetic membrane plane. The heterogeneity of variable and delayed PS-II fluorescence emission can be explained by the existence of two components: one of them is related to pigment-protein complex of PS-II (PPC-II) structurally and migrationally connected with LH-complex (alpha-component), but the other one--to PPC-II setting apart from the main LH-complex bulk (beta-component).

[Spectral anisotropy of chloroplasts, subchloroplast particles and pigment-protein complexes]. / Spektral'naia anizotropiia khloroplastov, subkhloroplastnykh chastits i pigment-belkovykh kompleksov.

Anisotropic properties of pea chloroplasts, subchloroplast fragments (photosystem 1 particles and pigment-protein complexes) and the blue-green algae oriented in polyacrylamide gel were investigated. It was shown that linear dichroism spectra of chloroplasts are the superposition of the corresponding spectra for the main light harvesting complex (HMLC) and P 700 chlorophyll a--protein complex (CP 1). Anisotropic properties of the photosystem 1 particles and blue-green algae are mainly caused by CP 1 anisotropy. Qy-transition moments tend to perpendicular orientation to the membrane plane for the Chl. b 649, Chl. a 660 and parallel orientation--for Chl. b 654, Chl. a 682. The degree of Qy-transition moments parallel orientation is higher for the longwave forms (Chl. a 690, Chl. a 702, Chl. a 712), than for the shortwave ones and coincides with this degree for the reaction centre pigment P 700 transition moment. It is suggested that the specific orientation of the pigment-protein complexes in the chloroplast membrane is important for the regulation of the spillover between two photosystems.

[Chlorophyll phosphorescence in chloroplasts and their fragments]. / Fosforestsentsiia khlorofilla v khloroplastakh i ikh fragmentakh.

Spectral parameters, decay time and quantum yield of low temperature (--196 degrees) delayed luminescence of chloroplasts and chloroplasts fragments have been investigated. It has been shown that the fragments enriched in photosystem 2, photosystem 1 of stroma or grana, obtained by differential centrifugation after digitonin treatment produce a delayed emission with components similar to that of initial chloroplasts, normal leaves and alga; i. e. phosphorescence (maximum 960--980 nm) and delayed fluorescence (maxima at 690 and 740 nm) of chlorophyll and phosphorescence of pigments of different nature (780--820 nm). Excitation spectra of chlorophyll phosphorescence have the maximum at 669 +/- 1 nm and shoulder at 650 nm. The quantum yield of chlorophyll phosphorescence in chloroplast is found to be lower than that of chlorophyll in ethanol by the factor of 200. It increases with destruction of initial structures reaching the maximal value in the most light fragments. The data suggest that the luminescence studied accompanies desactivation of the triplet states of the chlorophyll molecules involved in the photosynthetic pigment complex. On the basis of previous studies it has been proposed that the increase of phosphorescence intensity in the light particles is due to disturbances in the pigment complex leading to a decrease of triplet-triplet energy transfer from chlorophyll to carotenoids.

[Photochemical and spectral properies of the photosystem I reaction centers-enriched particles]. / Fotokhimicheskie i spektral'nye svoistva chastits, obogashchennykh reaktsionnymi tsentrami fotosistemy I.

The photosystem I reaction centers-enriched particles (RCP) having the ratio of P700/chlorophyll of 1 : 20--1 :30 were prepared from stroma lamellae photosystem subchloroplast fragments by extraction with water-saturated ether. The EPR signals and light-induced absorption changes indicate that the reaction centers are active in the particles. The spectral properties of the RCP were characterized. The main red absorption maximum is located at 673--674 nm with a "shoulder" at about 684--688 nm. A comparative analysis of the subchloroplast fragments and RCP absorption and fluorescence spectra suggests that the chl. a forms absorbed in the region of 680--695 nm are more closely associated with the reaction center. The most long-wavelength absorbing chl. a forms with maxima around 730--740 nm in the low temperature fluorescence spectra were not found in the RCP.