Luthein-5,6-epoxide cycle: A new xanthophyll cycle in chloroplasts of higher plants

The review gives a general description of the luthein-5,6-epoxide cycle recently found in higher plants. The cycle is localized in chloroplast membranes; its functioning depends on light intensity. Characteristics of the luthein-5,6-epoxide cycle are compared with the widely spread and well-studied violaxanthine cycle. It is supposed that some enzymes, such as violaxanthine deepoxidase and zeaxantine epoxidase, can participate in both of these cycles. It is also possible that violaxanthine deepoxidase and various zeaxantine epoxidases-ordinary or modified due to mutations-can be involved in these cycles.