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Synthetic model of the asymmetric [Mn3CaO4] cubane core of the oxygen-evolving complex of photosystem II

SprMorn 添加于 2012/6/8 14:29:27  1566次阅读 | 1次推荐 | 0个评论

The laboratory synthesis of the oxygen-evolving complex (OEC) of photosystem II has been the objective of synthetic chemists since the early 1970s. However, the absence of structural information on the OEC has hampered these efforts. Crystallographic reports on photosystem II that have been appearing at ever-improving resolution over the past ten years have finally provided invaluable structural information on the OEC and show that it comprises a [Mn3CaO4] distorted cubane, to which is attached a fourth, external Mn atom, and the whole unit attached to polypeptides primarily by aspartate and glutamate carboxylate groups. Such a heterometallic Mn/Ca cubane with an additional metal attached to it has been unknown in the literature. This paper reports the laboratory synthesis of such an asymmetric cubane-containing compound with a bound external metal atom, [(1)] . All peripheral ligands are carboxylate or carboxylic acid groups. Variable-temperature magnetic susceptibility data have established 1 to possess an S = 9/2 ground state. EPR spectroscopy confirms this, and the Davies electron nuclear double resonance data reveal similar hyperfine couplings to those of other MnIV species, including the OEC S2 state. Comparison of the X-ray absorption data with those for the OEC reveal 1 to possess structural parameters that make it a close structural model of the asymmetric-cubane OEC unit. This geometric and electronic structural correspondence opens up a new front in the multidisciplinary study of the properties and function of this important biological unit.

作 者:Shreya Mukherjeea, Jamie A. Stullb, Junko Yanoc, Theocharis C. Stamatatosa, Konstantina Pringouria, Troy A. Stichb, Khalil A. Abbouda, R. David Brittb, Vittal K. Yachandrac, and George Christoua,1
期刊名称: Proceedings of the National Academy of Sciences
期卷页: 02/14/2012 第109卷 第7期 2257~2262页
学科领域:生命科学 » 植物学 » 植物生理与生化
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原文链接:http://www.pnas.org/content/109/7/2257.abstract?sid=fe1febd8-2dca-4e08-9923-ded5cd40c4ff
DOI: 10.1073/pnas.1115290109
ISBN: 0027-8424
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相关报道: http://paper.sciencenet.cn/htmlpaper/20126814365951424854.shtm
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