The xanthophyll cycle - molecular mechanism and physiological significance

摘要: The light-dependent, cyclic changes of xanthophyll pigments: violaxanthin, antheraxanthin and zeaxanthin, called the cycle, have been known for about fifty years. This process was characterised higher plants, several fern moss species in some algal groups. Two enzymes, violaxanthin de-epoxidase (VDE) zeaxanthin epoxidase (ZE), belonging to lipocalin protein family, are engaged cycle. VDE requires its activity ascorbic acid reversed hexagonal structure formed by monogalactosyldiacylglycerol. ZE, postulated be a flavoprotein, has not purified yet it is from gene sequence only. Zeaxanthin epoxidation dependent on reducing power NADPH presence additional proteins. cycle play role many important physiological processes. Zeaxanthin, under high light conditions, thought main photoprotector autotrophic cells due ability dissipate excess absorbed energy that can measured as non-photochemical quenching. In addition formation protection thylakoid membranes against lipid peroxidation. Other functions which include regulation membrane physical properties, blue reception abscisic synthesis, also discussed.