ИСТИНА

Activation of biomolecules by light triggers structural and optical-property changes resolved by X-ray structure determination and spectroscopy experiments, respectively. Quantum chemistry calculations naturally provide a link between structure and optical properties, and hence, they become indispensable in studies of biomolecular photoactivation mechanisms. This talk will present three examples of complementing the structural data by quantumchemistry computations that facilitated search for a plausible biomolecular mechanism explaining the observed optical changes. The first example is the photoactivation reaction of the BLUF photoreceptor, for which combining the structure and computational studies suggested the photoactivation reaction and confirmed the structure of the thermally stable dark-adapted receptor state. In the second example – the FAP photoenzyme – the computational studies elucidated the role of the unusually bent oxidized flavin cofactor in facilitating the photoinduced electron transfer reaction. The final example addressing the lightinduced DNA repair by photolyases outlines the capability of time-resolved protein crystallography and electronic-structure calculations in characterizing electron-transfer pathways in biomolecules.