* To whom correspondence should be addressed.
Received December 29, 2007; Revision received April 22, 2008
Most firefly luciferases demonstrate a strong pH-dependence of bioluminescence spectra. Gene region encoding first 225 residues of Luciola mingrelica luciferase was subjected to random mutagenesis, and four mutants with altered pH-sensitivity of bioluminescence spectra were isolated. F16L substitution showed distinctly lower pH-dependence of bioluminescence spectra, and Y35N,H and F16L/A40S substitutions resulted in the enzymes with bioluminescence spectra virtually independent from pH in the range of 6.0-7.8. The structural explanation is proposed for the effect of mutations on pH-sensitivity of bioluminescence spectra.
KEY WORDS: firefly luciferase, random mutagenesis, mutation of amino acid residues, bioluminescence spectra, pH dependence of bioluminescence spectra