Light-driven Reconfiguration of a Xanthophyll Violaxanthin in the Photosynthetic Pigment-protein Complex LHCII: A Resonance Raman Study

Wojciech Grudziński, Ewa Janik, Joanna Bednarska, Renata Welc, Monika Zubik, Karol Sowiński, Rafał Luchowski and Wiesław I. Gruszecki

Resonance Raman analysis of the photosynthetic complex LHCII, immobilized in a polyacrylamide gel, reveals that one of the protein-bound xanthophylls, assigned as violaxanthin, undergoes light-induced molecular reconfiguration. The photo-transformation is selectively observed in a trimeric structure of the complex and is associated with a pronounced twisting and a trans-cis molecular configuration change of the polyene chain of the carotenoid. Among several spectral effects accompanying the reconfiguration there are ones indicating a carotenoid triplet state. Possible physiological importance of the lightinduced violaxanthin reconfiguration as a mechanism associated with making the pigment available for enzymatic deepoxidation in the xanthophyll cycle is discussed.