Theoretical aspects of the adenosine triphosphate bioluminescence assay based on the use of the firefly luciferin-luciferase system are considered, as well as its application for assessing cell viability in microbiology, sanitation, medicine, and ecology. Various approaches for the analysis of individual or mixed cultures of microorganisms are presented, and capabilities of the method for investigation of biological processes in live cells including necrosis, apoptosis, as well as for investigation of the dynamics of metabolism are described.

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Single mutants (C62S, C62V, C86S, C146S, C164S), double mutants (C62/146S, C62/164S, C86/146S, C146/164S), and triple mutant C62/146/164S of the Luciola mingrelica firefly luciferase carrying C-terminal His(6)-tag were obtained on the basis of plasmid pETL7 by site-directed mutagenesis. Bioluminescence and fluorescence spectra were not altered by the introduced mutations. In the case of mutants C86S, C86/146S, C62/164S, and the triple mutant C62/146/164S, the K(m)(ATP) and K(m)(LH)(2) values were increased by a factor of ~1.5-1.9. Their expression level, specific activity, and thermal stability were significantly decreased. The other mutations had almost no effect on the K(m)(ATP) and K(m)(LH)(2) values, specific activity, and thermal stability of the enzyme. Thermal stability of the C146S mutant was increased by a factor of ~2 and 1.3 at 37 and 42°C, respectively. The possible mechanism of the influence of these mutations on properties and structure of the enzyme is discussed.