ABSTRACT
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.
