Direct determination of the excited state energies of the xanthophylls diadinoxanthin and diatoxanthin from Phaeodactylum tricornutum

Higher plant and algal photosynthetic organisms interconvert xanthophylls in response to changes in solar light levels to provide photoprotection against high light stress. One proposed molecular mechanism for this process involves direct quenching by xanthophylls of excess excited state energy of chlorophyll. The present work has measured the precise excited state energies of two interconverting xanthophylls, diadinoxanthin and diatoxanthin. The data address the energetic feasibility of the direct quenching mechanism of photoprotection in marine algae.