DAILY XANTHOPHYLL.CYCLE PHOTOPROTECTION IN DEVELOPING LEAVES

There is widespread agreement that the xanthophyll cycle provides a major photoprotection system for photosynthesis in green leaves (l-8). Indeed this type of photoprotection seems to be ubiquitous for photosynthetic organisms. Photoprotection is provided via a rapid, near 1013 set, ability of zeaxanthin (Z) to dissipate excess light energy from photosynthesis because the energy of the excited singlet state of Z is lower than that of chlorophyll a (9). Details of historical and current understandings on the operation of the xanthophyll cycle in green tissues are readily available (3,6,9, A.M. Gilmore- these Proceedings). During initial research efforts to establish the xanthophyll cycle some developing photosynthetic tissues were appropriately used, e.g., to identify the pigments involved or to detect the enzymes required for epoxidation and deepoxidation. However these developing tissues were not subjected to natural plant diurnal growth conditions and this may have obscured cycle functions during the development of photosynthesis. For example; red kidney bean plants were dark grown for 4 days followed by giving I-msec flashes of Xenon light every 12 minute

THE TRIPLET STATES OF THE PHOTOSYNTHETIC PIGMENTS IN VITRO AND IN VIVO

The spectroscopy of the triplet state has been applied to the investigation of the primary processes of the energy and electron transfer in the photosynthesizing purple bacteria and photosystem II of the higher plants. The complex of methods, using the effects of the outside magnetic field and the phenomenon of the electron paramagnetic resonance has been developed. The information about the magnetic interactions and kinetic parameters of the predecessor of the triplet state of the reaction centres - the primary radical pair has been obtained. The range of the electron paramagnetic resonance triplet states has been widened to the room temperatures. This allowed to investigate the processes of the triplet-triplet transfer of energy in the reaction centres and magnetic interactions of the triplet states. It has been shown, that the character of the spin polarization of the triplet state allows to easily identify the mechanism of its invasion. The appearance and the reasons of the heterogenicity of the reaction centres bacterial preparations have been analyzed. The first detailed model of structure of the reaction centre first donor of the photosystem II has been offered. The reasons of the universal organisation of the reaction centre primary donor in the form of the molecular dimer have been justified.Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

ASSOCIATION OF NADF-MALATE (DECARBOXYLATING) DEHYDROGENASE AND DECARBOXYLATION PHASE ENZYMES OF MAIZE

The investigation objects are the leaf of the maize sprouts. The aim is to extrast, clean and prove the functioning of the associate consisting of the NADF-malate (decarboxylating) dehydrogenase and enzymes of the Calvin cycle carboxylation phase. Two procedures for enzymating synthesis of the L-malic and labelled according to the carbon (*991*994C) in the fourth position have been developed, and with its use the ability of the associate to perform the "tunnelling" the *991*994C-labelled fragment from malic acid into the phosphoglyceric acid has been demonstrated firstly.Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio