The distinctive features of firefly luciferase bioluminescence are the complex spectral changes of the form and symbol 108 \f "Symbol" \s 12lмакс of bioluminescence under variation of pH, temperature, and enzyme structure. Analysis of the literature data and the own results of the authors on the nature of the emitter in luciferin-luciferase system leads to the conclusion that the keto-enol tautomerism of oxyluciferin molecule the most authentically explains observable complex spectral changes. Each molecule of luciferase can contain only one molecule of the emitter at the moment of bioluminescence. Hence, the emitter can be considered as the intramolecular label, characterizing the properties of its microenvironment in the active center of the enzyme. Superposition of two or three forms of the emitter recorded in bioluminescence spectra indicates that various conformational forms of the enzyme co-exist in the reaction medium, that are in a dynamic equilibrium, each of which generates one of the emitter forms.
bioluminescence, firefly luciferase, keno-enol tautomerism, oxyluciferin
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