Orange carotenoid protein (OCP) is a carotenoid-binding protein involved in photo-protection mechanisms of cyanobacteria. Upon exposure to high light, OCP interconverts from an orange resting form (OCPo) to a red active one (OCPr); the mechanism of this interconversion, even if extensively studied, has still not been fully elucidated. In this work, we use multiscale atomistic models ranging from classical to hybrid quantum-classical (QM/MM) molecular dynamics to give a comprehensive molecular explanation of the drastic spectroscopic changes observed upon interconversion. The findings are finally used to formulate a new hypothesis on the role of the protein in the photoactivation mechanism.
Link: https://www.cell.com/chem/fulltext/S2451-9294(19)30468-1
