Light and Heat Induced Denaturation of Photosystem II Core Antenna Complex CP47

Light and heat induced denaturation of CP47, the core antenna complex of photosystem Ⅱ purified from spinach, were investigated using absorption and circular dichroism spectra. Light caused the destruction of chlorophyll a and excitonic interaction of chlorophyll a in CP47, while the protein secondary structure was not apparently changed. Heat induced the destruction of protein secondary structure and excitonic interaction of chlorophyll a, but the chlorophyll a molecule was not damaged. The results suggest that both the chlorophyll a molecular structure and the protein native conformation are necessary for excitonic interaction of chlorophyll a and the energy transfer function of the chlorophyll a binding protein.