Structural Changes and Non-Photochemical Quenching of Chlorophyll a Fluorescence in Oxygenic Photosynthetic Organisms

摘要: This chapter focuses on the nature, physical mechanism and physiological significance of structural changes at different levels complexity photosynthetic apparatus oxygenic organisms – with special emphasis non-photochemical quenching (NPQ) singlet-excited state chlorophyll a. The dual role antenna system, light harvesting under low thermal dissipation high light, requires substantial flexibility. Indeed, reversible induced by excess-light excitation have been observed in via several techniques, including electron microscopy, scattering measurements, circular dichroism spectroscopy, small-angle neutron scattering. These investigations revealed reorganizations level (i) ultrastructure thylakoid membranes, affecting repeat distances, (ii) macro-organization light-harvesting complexes within membrane, perturbing ordered arrays complexes, as well (iii) isolated systems. In some cases, correlations between NPQ established. many however, relationship or membranes remains to be explored. Nevertheless, currently available data strongly suggest that, while an overall reorganization is a necessary condition for adjusting functional activities growth intensities photoprotection, particular, per se not sufficient (that also presence effector molecules, such as, e.g., PsbS zeaxanthin). deals effect excess energy apparatus: light-induced systems vivo vitro, rates linearly proportional intensity used photosynthesis). proposed driven what termed thermo-optic mechanism: elementary elicited ultrafast local heat transients due photon energy, photophysical feedback that appears modulate regulate enzymatic functions complexes.