Effect of Viscous Media on the Quantum Yield of Bioluminescence in a Reaction Catalyzed by Bacterial Luciferase

Based on the data on the transient kinetics of the bioluminescent reaction catalyzed by P. leiognathi luciferase in media with polyols and sugars, the relative quantum yield of bioluminescence in this reaction per substrate molecule was determined using mathematical modeling. It was obtained that in some media the relative quantum yield per aldehyde molecule increases compared to the value in the buffer: by 18 and 33% in the presence of glycerol and sucrose, respectively. Molecular dynamics methods were used to analyze the side-chain conformation of αHis44 – a residue of bacterial luciferases that is known to play an essential role in catalysis. It was found that in the presence of all cosolvents an increased frequency of occurrence of the αHis44 conformation, which is optimal for catalysis, is observed. This effect can contribute to the observed increase in the quantum yield of bioluminescence of the studied reaction in viscous media.