of dielectric properties of media on kinetic parameters of bioluminescent reac- tion of luciferas... more of dielectric properties of media on kinetic parameters of bioluminescent reac- tion of luciferase of Vibrio harveyi was studied with addition of organic solvents (ethanol, methanol, acetone, ethylene glycol, formamide and dimethyl sulphoxide). Small con- centration of organic solvents (0.5{18% v/v) can both activate and inhibit intensity of luminescence depending on the their physical-chemical properties, higher concentrations inhibit bioluminscence in vitro. The interaction of kinetic parameters of bioluminescent reaction and dielectric permittivity of the medium " cannot be described by a unied dependence. With addition of solvents when " ranges from 74 to 82 increase of the maximum reaction rate depends on the balance between the capacity of the solvent to form hydrogen bonds and moderate hydrophobic contacts. Addition of formamide at- tenuates electrostatic interactions and increases the decay rate of excited emitter. High (compared to alcohols) electron-donor capacit...
The interaction of luciferases from two types of luminous bacteria, Photobacterium leiognathi and... more The interaction of luciferases from two types of luminous bacteria, Photobacterium leiognathi and Vibrio harveyi, with their substrates [the photorecovered FMNH2 and long-chain aldehydes--decanal (C10), dodecanal (C12) and tetradecanal (C14)] in water-organic media was analysed using kinetic graphical methods. Moderate concentrations of organic solvents have been demonstrated to activate the bioluminescence, while higher concentrations inhibit it. The interactions of these effectors with luciferases show different types of kinetics, which depend on concentrations of solvents, kinds of enzymes and substrates. The apparent value of the Michaelis constant, Km, for C14 of both luciferases and for C10 of luciferase V. harveyi is enhanced with increasing concentration of the organic solvent, but Km for C12 and C10 of luciferase P. leiognathi decreases. Obviously, at the specific binding of aldehydes with luciferases in the first case, hydrophobic interactions are realized, but in second, the electrostatic interactions are realized. The series of changes in parameters of bioluminescence reaction catalysed by different luciferases is obviously determined by their structural peculiarities.
The acidic lectin from winged bean (Psophocarpus tetragonolobus), WBAI1, is an N-glycosylated dim... more The acidic lectin from winged bean (Psophocarpus tetragonolobus), WBAI1, is an N-glycosylated dimeric protein of molecular weight 58kD. It binds strongly to the H-antigenic determinant on human erythrocytes and also to the T-antigenic disaccharide GaI-131,3-GalNAc. Crystals of WBAII in complex with methyl-ct-D-galactose were obtained in two different forms. The structures were solved by the molecular replacement method using the coordinates of the basic form of winged bean lectin (WBAt), and refined. Clear density for the bound carbohydrate could be seen in the Fourier maps. The strucure provided details of protein-carbohydrates interactions. A close examination of the binding site with modelled sugars revealed the structural basis for the strong affinity of WBAII for the H-antigen and other teminally monofucosyJated carbohydrates. It was also possible to explain the differences in the specificities of WBAII and WBAI, which binds only to the A-and B-type antigens but not to the H-antigen, from this analysis.
of dielectric properties of media on kinetic parameters of bioluminescent reac- tion of luciferas... more of dielectric properties of media on kinetic parameters of bioluminescent reac- tion of luciferase of Vibrio harveyi was studied with addition of organic solvents (ethanol, methanol, acetone, ethylene glycol, formamide and dimethyl sulphoxide). Small con- centration of organic solvents (0.5{18% v/v) can both activate and inhibit intensity of luminescence depending on the their physical-chemical properties, higher concentrations inhibit bioluminscence in vitro. The interaction of kinetic parameters of bioluminescent reaction and dielectric permittivity of the medium " cannot be described by a unied dependence. With addition of solvents when " ranges from 74 to 82 increase of the maximum reaction rate depends on the balance between the capacity of the solvent to form hydrogen bonds and moderate hydrophobic contacts. Addition of formamide at- tenuates electrostatic interactions and increases the decay rate of excited emitter. High (compared to alcohols) electron-donor capacit...
The interaction of luciferases from two types of luminous bacteria, Photobacterium leiognathi and... more The interaction of luciferases from two types of luminous bacteria, Photobacterium leiognathi and Vibrio harveyi, with their substrates [the photorecovered FMNH2 and long-chain aldehydes--decanal (C10), dodecanal (C12) and tetradecanal (C14)] in water-organic media was analysed using kinetic graphical methods. Moderate concentrations of organic solvents have been demonstrated to activate the bioluminescence, while higher concentrations inhibit it. The interactions of these effectors with luciferases show different types of kinetics, which depend on concentrations of solvents, kinds of enzymes and substrates. The apparent value of the Michaelis constant, Km, for C14 of both luciferases and for C10 of luciferase V. harveyi is enhanced with increasing concentration of the organic solvent, but Km for C12 and C10 of luciferase P. leiognathi decreases. Obviously, at the specific binding of aldehydes with luciferases in the first case, hydrophobic interactions are realized, but in second, the electrostatic interactions are realized. The series of changes in parameters of bioluminescence reaction catalysed by different luciferases is obviously determined by their structural peculiarities.
The acidic lectin from winged bean (Psophocarpus tetragonolobus), WBAI1, is an N-glycosylated dim... more The acidic lectin from winged bean (Psophocarpus tetragonolobus), WBAI1, is an N-glycosylated dimeric protein of molecular weight 58kD. It binds strongly to the H-antigenic determinant on human erythrocytes and also to the T-antigenic disaccharide GaI-131,3-GalNAc. Crystals of WBAII in complex with methyl-ct-D-galactose were obtained in two different forms. The structures were solved by the molecular replacement method using the coordinates of the basic form of winged bean lectin (WBAt), and refined. Clear density for the bound carbohydrate could be seen in the Fourier maps. The strucure provided details of protein-carbohydrates interactions. A close examination of the binding site with modelled sugars revealed the structural basis for the strong affinity of WBAII for the H-antigen and other teminally monofucosyJated carbohydrates. It was also possible to explain the differences in the specificities of WBAII and WBAI, which binds only to the A-and B-type antigens but not to the H-antigen, from this analysis.
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Papers by I. Sukovataya