Seeing how plants split water: "Reporting online in the journal Science today Imperial researchers reveal the fine detail of the protein complex that drives photosynthesis..
Photosynthesis occurs in plants, some bacteria and algae and involves two protein complexes, photosystem I, and photosystem II - which contains the water-splitting center. While previous models of PSII function have sketched out a picture of how the water splitting center might be organized, the Imperial team were able to reveal the structure of the centre at a resolution of 3.5 angstroms (or one hundred millionth of a centimetre) in the cyanobacterium, Thermosynechococcus elongatus by combining the expertise of Professor So Iwata in solving protein structures and Professor Jim Barber in the photosynthetic process.
"Results by other groups, including those obtained using lower resolution X-ray crystallography at 3.7 angstroms have shown that the splitting of water occurs at a catalytic center that consists of four manganese atoms (Mn)," explains Professor So Iwata of Imperial's Department of Biological Sciences. "We've taken this further by showing that three of the manganese atoms, a calcium atom and four oxygen atoms form a cube like structure, which brings stability to the catalytic center. The forth and most reactive manganese atom is attached to one of the oxygen atoms of the cube. Together this arrangement gives strong hints about the water-splitting chemistry.
"Our structure also reveals the position of key amino acids, the building blocks of proteins, which provide a details of how cofactors are recruited into the reaction centre," Barber said. "PSII is truly the 'engine of life' and it has been a major challenge of modern science to understand how it works. Manufacturing hydrogen from water using the photosynthetic method would be far more efficient than using electrolysis" 9:01:44 AM