Light-dependent delta mu Na-generation and utilization in the marine cyanobacterium Oscillatoria brevis.

Light-dependent Na+ and H+ transports, membrane potential (delta psi) and motility have been studied in the cells of the marine cyanobacterium Oscillatoria brevis. In the presence of a protonophorous uncoupler, carbonyl cyanide-m-chlorophenylhydrazone, the intracellular Na+ level is shown to increase in the dark and decrease in the light. The Na+/H+ antiporter, monensin, stimulates the dark CCCP-dependent [Na+]in increase and abolishes the light-dependent [Na+]in decrease. Na+ ions are necessary for the fast light-induced delta psi generation and H+ uptake by the cells. This uptake is inhibited by monensin being resistant to CCCP. Monensin sensitizes the delta psi level and the motility rate to low CCCP concentrations. The obtained data are consistent with the assumption that O. brevis possesses a primary Na+ pump which utilizes (directly or indirectly) the light energy.

[Polarization of the intrinsic fluorescence of proteins. I. Factors determining the form of the polarization spectrum]. / Poliarizatsiia sobstvennoi fluorestsentsii belkov. I. Faktory, opredeliaiushchie formu poliarizatsionnogo spektra.

The dependence of the slopes of normalized Perrin plots on the excitation wavelength was established. It was shown that the cause of this effect is the anisotropy of the Brownian rotation of proteins, which must be regarded as asymmetrical particles with specific, but not random, orientation of tryptophan with respect to the main axes of the macromolecule. These findings were analysed on the basis of the rotational depolarization theory of such systems, applied for the case when bands of two absorption oscillators overlap as it is for oscillators 1La and 1Lb in the longest wavelength absorption band of tryptophan. It was shown that anisotropy of Brownian molecular rotation is one of the factors that determines the form of the polarization spectrum. The difference of the polarization spectrum of proteins from that of tryptophan, extrapolated to the infinite viscosity, is determined by energy transfer processes in proteins.