Nanoparticles of water-soluble dyads based on amino acid fullerene C60 derivatives and pyropheophorbide: Synthesis, photophysical properties, and photodynamic activity.

Synthesis, spectral properties, and photodynamic activity of water-soluble amino acid fullerene C60 derivatives (AFD) and four original AFD-PPa dyads, obtained by covalent addition of dye pyropheophorbide (PPa) to AFD, were studied. In aqueous solution, these AFD-PPa dyads form nanoassociates as a result of self-assembly. In this case, a significant change in the absorption spectra and strong quenching of the dye fluorescence in the structure of the dyads were observed. A comparison of superoxide or singlet oxygen generation efficiency of the studied compounds in an aqueous solution showed the photodynamic mechanism switching from type II (singlet oxygen generation of the native dye) to I type (superoxide generation of dyads). All dyads have pronounced phototoxicity on cells Hela with IC50 9.2 µM, 9.2 µM, 12.2 µM for dyads Val-C60-PPa, Ala-C60-PPa and Pro-C60-PPa, respectively. Such facilitation of type I photodynamic mechanism could be perspective against hypoxic tumors.

Antioxidant Activity of Tetranitrosyl Iron Complex with Thiosulfate Ligands and Its Effect on Catalytic Activity of Mitochondrial Enzymes In vitro.

The antioxidant and antiradical properties of the tetra nitrosyl iron complex with thiosulfate ligands (TNIC) were studied in vitro in mouse brain homogenates. It was found for the first time that TNIC is an effective antioxidant. The effect of TNIC on the catalytic activity of mitochondrial enzymes cytochrome c oxidase and monoamine oxidase A was studied. It was shown for the first time that TNIC is an inhibitor of the catalytic activity of cytochrome c oxidase and monoamine oxidase A in animal brain mitochondria in vitro.

Gold helps bacteria to oxidize methane.

With the use of labeled methane-14C and by chromatographic analysis it was shown that gold-containing protein ("Au-protein"), isolated from goldphilic Micrococcus luteus bacteria, catalyzes the oxidation of methane to methanol in the system also containing NADH, air, K(3)Fe(CN)(6) and Tris-HCl buffer. Presumably Au-protein helps bacteria to survive when usual sources of carbon and energy are scarce.

Participation of biological membranes in colloidal gold transformation by Micrococcus luteus cells.

Methods of biochemical and physicochemical analysis were applied for studying the role of Micrococcus luteus cell structure in gold accumulation. It was shown that membrane proteins were the main factors in this process. Moreover, different quinones played the main role in the redox transformation of gold.

[Statistical analysis of electron microphotographs of bioobjects, labelled by electron-dense mercarbide markers]. / Statisticheskii analiz élektronnykh mikrofotografii bioob''ektov, mechennykh élektronno-plotnymi merkarbidnymi metkami.

A method of statistical processing of electron micrographs of molecular objects modified by electron-dense labels containing mercury is proposed. The method allows one to study size, degree of modification and heterogeneity of objects. Application of the method for study of modified nitrogenase and its Fe-Mo containing co-factor, lysozyme, myoglobin, sodium thiomolybdate and trichlortriazine has shown the features of chemical modification and electron micrographs of these molecules. The method can be used for processing of data about complex biological objects modified by electron-dense labels.

[Study of the topography of the nitrogenase active center by the electron microscopy method with the use of the electron density labels]. / Izuchenie topografii aktivnogo tsentra nitrogenazy metodom elektronnoi mikroskopii s primeneniem elektronoplotnykh metok.

The electron microscopy method has been used for studying the topography of the active centre of the nitrogenase in combination with the method of electron density labels. The active centre has been shown to place on the nitrogenase macromolecule asymmetrically. The non-heme iron atoms of the nitrogenase active centre have been regularly packed and located on the macromolecule as a quadrangular cluster closely to the surface of subunits. Two free sulfhydryl groups of the ATP-site of the nitrogenase active centre are in close proximity to the cluster. ATP-site of the nitrogenase active centre containing these groups is located on the Fe-enzyme, while the main part of the iron-containing cluster is located on the Mo-Fe-enzyme.

[Isotopic effect in enzymatic oxidation of methane]. / Izotopnyi effekt v fermentativnom okislenii metana

The isotopic effect during oxidation of methane and deuteromethane by a suspension of Methylomonas rubrum cells, for which methane is the only source of carbon, was observed. The rate of CH4 oxidation is 12.5 times higher than that of CH4 oxidation. It is demonstrated that CD4 is a competitive inhibitor of CH4 oxidation. The results obtained suggest that the disruption of the C-H bond is the limiting step of enzymatic oxidation of methane.