Enhanced Protein Photo-Stability Analysis Using SRCD in the Presence of Phospholipid SUVs

The interaction between lipids and proteins impacts a multitude of cellular processes and may contribute to the onset of several pathologies and aging. Such processes are frequently linked to oxidative stress, whereby polyunsaturated fatty acids act as substrates for in vivo lipoxidation. The subsequent lipid peroxidation and/or isomerization is known to affect membrane organization, as well as to modify proteins and DNA, leading to functional alterations. The aim of this study was to evaluate the capacity of UV-denaturation experiments to induce lipid modification and to investigate the influence of lipid presence on the conformational stability of selected soluble model proteins. The high photon flux and brilliance of the incident beam light of Diamond Light Source B23 for sinchrotron radiation circular dichroism (SRCD) was used to induce protein denaturation. This was acheived by scanning 30 repeated consecutive SRCD spectra in the far-UV region that, being diagnostic of protein folding, enabled the estimation of the protein photostability. Our findings show that the presence of lipid vesicles (SUVs) significantly impacts the UV denaturation of proteins, preserving the native structure in proteins with a high helical content. This suggests that lipids may play a protective role against light-induced damage to proteins.