ANALYSIS OF SPECTRAL CHARACTERISTICS OF BOVINE SERUM ALBUMIN UNDER LONG-WAVE QUASIMONOCHROMATIC UV EXPOSURE
The impact of high-energy radiation on proteins is usually associated with the absorption of light energy by its chromophore groups. However, a chain of conformational transformations in a molecule can arise not only as a result of the direct action of light quanta, but also as a result of the action of active oxygen metabolites generated during water photolysis. Photolysis of water, based on the direct decomposition of the molecule under the influence of absorbed light quanta, can occur at an energy absorption of about 237.4 kJ/mol. However, the greatest efficiency of this process is observed as a result of exposure to light quanta with a wavelength of less than 400 nm, which corresponds to approximately 293 kJ/mol. But if the process of water photolysis is considered not before the release of end products in the form of molecular oxygen and hydrogen, but before the formation of reactive oxygen species, then the energy barrier decreases to 1.23 eV As a result, under the action of long-wavelength UV radiation, cascades of photochemical reactions can be triggered, which have an indirect effect on proteins. This makes it particularly interesting to study the influence of this part of the spectral range on the physicochemical characteristics of albumin, in order to separate the effects of direct and indirect effects of UV radiation. The effect of long-wave UV radiation on the spectral characteristics of the monomeric and dimeric forms of bovine serum albumin was studied by recording electronic absorption spectra. The unequal photosensitivity of the investigated biomacromolecules is shown. It has been established that, due to the absence of chromophores capable of absorbing the energy of light quanta with a wavelength of about 365 nm, the photoinduced changes in the spectral characteristics of the protein recorded by us make it possible to reveal the appearance of a chain of conformational transformations induced by the processes of oxidative modification of the protein due to the formation of reactive oxygen species resulting from the photolysis of water.