L. A. Frank
Institute of Biophysics, Siberian Branch of the Russian Academy of Sciences, Russia
Dr. Ludmila A. Frank got her Ph.D. degree in Biophysics (1997) and Dr. of Sciences degree in Biology (2010) at the Institute of Biophysics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk. At present, she is a leading researcher of the Institute and Professor of the Siberian Federal University. Her research interests are concerned with investigating structure and function of light-emitting proteins and development of analytical systems on their base. She is the author and co-author of more than 100 publications and several international and Russian patents.
Nowadays, the light-emitting proteins are the promising analytical tool for both in vitro and in vivo applications to meet the growing demands of science and medicine. The great part of analytical techniques is based on coelenterazine-dependent bioluminescent systems derived from luminous marine organisms. Bioluminescent signal in the organisms arises as a result of coelenterazine (CE) oxidation catalyzed by special enzymes, luciferases. The CE-dependent luciferases of different origin (coelenterates, ctenophores, copepods, ostracods, etc.) known for today are relatively small single-chain proteins having nothing common but a substrate. Luciferases of special type, Ca2+-regulated photoproteins, are stable complexes of apophotoprotein and pre-oxidized substrate molecule – peroxycoelenterazine, which is strongly but non-covalently immobilized in the protein hydrophobic cavity. Bioluminescent reaction is triggered with Ca2+ producing coelenteramide, CO2, and a flash of blue light. Several CE-dependent luciferases are comprehensively studied as to biochemical properties, tertiary structures, bioluminescence mechanism etc. Application of photoproteins and luciferases as reporters in binding assay has many prospects due to the high quantum yield of bioluminescent reaction, providing high-sensitivity detection; assay robustness, reproducibility, and safety. Of special interest is the use of luciferases genetically modified so to obtain novel enzymes with unique properties such as shifted bioluminescence spectra, varied kinetics, thermostability, or the enzymes fused with polypeptide modules (mini antibodies, biotinylated site, etc.) that are responsible for the assay specificity.