Function of beta-carotene and tocopherol in photosystem II.

New and known structural and functional insights in the role of beta-carotene and of alpha-tocopherol in photosytem II are reviewed. A concept is presented connecting the failure of P680 triplet quenching by beta-carotene with the formation of singlet oxygen and its scavenging in the turnover of the D1 protein and by tocopherol in the maintenance of PS II structure and function.