[Formation of free radicals at photoreduction of allophycocyanin B]. / Obrazovanie svobodnykh radikalov pri fotovosstanovlenii allofikotsianina B.

A photoinduced ESR signal is detected in the presence of 10(-2) M of dithionine in phycobilisomes and in fractions enriched in allophycocyanin B. The signal is characterized by the line width of 12G and g-factor of 2.004. It is demonstrated that the appearance of the free radicals is related to photoreduction of allophycocyanin B.

[Resolution of the structure of the absorption spectrum of blue-green algae by a method of measuring the 2d derivative at -196 degrees C]. / Razreshenie struktury spektra pogloshcheniia sine-zelenykh vodoroslei metodom izmereniia 2-i proizvodnoi pri -196 gradusov C.

By measuring the 2nd derivative at -196 degrees C the thin structure of the absorption spectrum of intact cells, isolated in phycobilisomes and pure pigments of blue-green algae Anabaena variabilis and Aphanizomanon flos-aquae is shown. 8 absorption bands in the region 669--710 nm pertaining to chlorophyll a in different aggregation region were found. Almost the same number of bands were found in the region 550--660 nm. The latter were conditioned by the absorption of allophycocyanin, phycocyanin, and probably by phycoerythrin present in the form of different associates.

Phycobilisomes from the blue-green algae Aphanizomenon flos-aquae and Anabaena variabilis.

Phycobilisomes (PBS) were isolated from Aphanizomenon flos-aquae and Anabaena variabilis. The absorption spectra and second derivative of the absorption spectra of isolated PBS indicate the presence of phycoerythrocyanin, and allophycocyanin. The fluorescence spectra of PBS were measured at room temperature and -196 degrees C. Undamaged PBS have the principal fluorescence maximum in the region of 660 nm at room temperature and in the region of 685-690 nm at -196 degrees. When the PBS were heated from ) to 60 degrees the fluorescence at 685-690 nm disappeared and it increased in the region of 650-660 nm. This is apparently due to disruption of the structure of PBS, which results in a disturbance in the migration of energy along the chain phycoerythrocyanin leads to phycocyanin leads to allophycocyanin.

[Light-induced absorption changes at 590 nm in isolated pea chloroplasts and their relation to plastocyanin]. / Svetoindutsiruemye izmeneniia absorbtsii pri 590 nm v izolirovannykh gorokha i ikh sviaz' s plastotsianinom.

The light-induced decrease in absorption with the minimum at 590-595 nm has been found in chloroplasts of etiolated pea seedlings by the method of dual-wavelength difference spectrophotometry. It has been shown that this effect is caused by photoreduction of the electron carrier with the absorption maximum of its oxidized form at 590 nm. Photoreduction of the carrier has been observed after excitation both by the short-wave (646 nm) and long-wave (709 nm) red light, although the latter is less effective. It has been suggested that the absorption changes at 590 nm are caused by light-induced redox conversions of plastocyanin bound to chloroplast membrane.

[The fluorescence method of peroxide determination in isolated chloroplasts]. / Fluorestsentnyi metod opredeleniia perekisi vodoroda v izolirovannykh khloroplastakh

High-sensitive method of peroxide estimation in suspension of pea chloroplasts is worked out. It is based on a decrease of esculatin fluorescence due to its oxidation by peroxide with peroxidase.