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

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

Abstract

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.