Light-Modulated Sunscreen Mechanism in the Retina of the Human Eye
Rafał Luchowski, Wojciech Grudziński, Renata Welc, Maria Manuela Mendes Pinto, Alicja Sęk, Jan Ostrowski, Łukasz Nierzwicki, Paweł Chodnicki, Miłosz Wieczór, Karol Sowinski, Robert Ręjdak, Anselm G M Juenemann, Grzegorz Teresiński, Jacek Czub, Wiesław I. Gruszecki
Abstract
photoisomerization. We explore this photochemically switchable system using chromatographic analysis coupled with microimaging based on fluorescence lifetime and Raman scattering, showing it at work in both isolated human retina and model lipid membranes. The molecular mechanism underlying xanthophyll reorientation is explained in terms of hydrophobic mismatch using molecular dynamics simulations. Overall, we show that xanthophylls in the human retina act as "molecular blinds", opening and closing on a submillisecond timescale to dynamically control the intensity of light reaching the photoreceptors, thus enabling vision at a very low light intensity and protecting the retina from photodegradation when suddenly exposed to strong light.