Ultrafast spectroscopy helped to understand the distribution of energy in photosynthesis

American and Italian scientists have studied the mechanism of redistribution of energy light-harvesting complex into artificial membrane similar to the processes that occur in the cells of green plants. It turned out that the process takes place in two ways, one of which has previously been assumed, but experimentally confirmed for the first time. The results of a study published in Nature Communications.

Green plants transfer solar energy into the energy of the formation of chemical bonds proceeds through a complex chain of reactions. It includes a network of protein-antennas: light-harvesting complexes in the membrane that absorb light and channel it to the reaction center where formed is the difference of charges, which starts the reaction of photosynthesis. Network proteins are also able to adapt to changing light conditions, to prevent the formation of harmful products of photochemical reactions kind of radicals.

When the light too much, the system is configured to dissipate excess energy by converting it into heat. This process is called non-photochemical quenching. Each light-harvesting complex is a series of photophysical processes on the transmission, energy distribution and the formation of harmful molecules. With a change in the conformation of proteins (the mutual arrangement of atoms of molecules in space) vary the length and effectiveness of these three processes. Given the fact that in photosynthesis involved a whole network of such complexes, to determine the balance between the transfer of energy and its redistribution, as well as their mechanisms is a complex task.

Antenna connect the network of primary (chlorophylls) and secondary (carotenoids) svetoprozrachnyh pigments in the plant, the electronic interaction between them provides a fast and efficient transfer of energy, which is used to initiate chemical reactions and redistributed.

In green plants, the main antenna is the so-called light-harvesting complex II (SSC), fotovista which studied quite a lot. It is assumed that a change in the conformation of the complex goes into a state of redistribution of energy. To study such conformational changes is very difficult, since the relative position of the atoms influenced by the environment in which there is a connection. To determine the photophysical ways of energy transformation in individual antennas is impossible, and attempts to influence the system by laser radiation leads to disturbing artifacts.

Min-Jung Son (Minjung Son) with colleagues from the Massachusetts Institute of technology with a very sensitive shirokopolosnoi ultrafast two-dimensional electronic spectroscopy have studied the photophysical processes in membrane SSC drive (nanodisc). Necessary protein, researchers have put in the drive of a double lipid layer that simulates the environment in which it is found in nature, but outside the context of the protein network.

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