Photosensitized modification of proteins: from oxidative stress to biocatalysis application

C. D. BORSARELLI

La Plata

Conferencia; XLVII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE BIOFÍSICA; 2018

Sociedad Argentina de Biofísica (SAB)

Solar light interaction with biological molecules plays several vital roles including photosynthesis, photosignalling, and circadian rhythm among others. Photon absorption produces excited states that depending on several reaction conditions driving to different photochemical pathways with biological consequences. Despite the direct absorption of solar UVB photons by proteins is highly minimized by the filtering of the ozone layer, the later does not avoid the occurrence of photosensitized processes, where UVA and visible photons are absorbed by other intrinsic or extrinsic chromophores inducing secondary reactive intermediates targeting protein residues. Here, we present some examples of photosensitized reactions involving organic and inorganic sensitizers with several proteins (e.g. albumins, lysozyme, synuclein, lipase, etc.) using visible light. Mechanistic aspects are discussed, e.g. involvement of molecular oxygen, charge-transfer reactions, and the results are analyzed in terms of the effect of the protein milieu on the molecular distribution and photophysical properties of the sensitizer, protein oxidation and crosslinking effects, etc. The impact of the photosensitized reactions is presented on the protein structure and functionality in an oxidative stress picture, and also for technological applications to obtain immobilized insoluble biocatalyst suitable for biodiesel production.