Sixth Rebeiz Foundation for Basic Research Paper Award

The Rebeiz Foundation for Basic Research (RFFBR) Paper Award for 2011 has been awarded to Dr. Theodore Agapie and his colleagues:Jacob Kanady, Emily, Y. Tsui, and Michael W. Day, for their paper entitled " A synthetic Model of the MN3Ca Subsite of the Oxygen-Evolving Complex in Photosystem II. The paper appeared in Science, 333:733-736 (2011).

In selecting this paper for the Sixth RFFBR Paper Award, the Board of directors of the Rebeiz Foundation felt that the described work that will greatly benefit other chloroplast researchers, and enhance our knowledge of photosystem II mode of action.

A Brief Summary of the Paper is Given Below
Biological dioxygen generation occurs within Photosystem II (PSII) in cyanobacteria and plants. The active site responsible for this transformation, the Oxygen Evolving Complex (OEC), consists of a Mn4CaOn cluster embedded in a large protein complex. Given the broad fundamental interest and potential applications of water splitting to make dioxygen, the structure of this cluster and the mechanism of catalysis have been the subject of many spectroscopic, computational, synthetic, crystallographic and biochemical studies. Despite significant advances, the mechanism of oxygen production is still not well understood. The role of different metals within the catalytic cycle and the site of O-O bond formation are debated. The large protein matrix has complicated direct studies of the OEC active site and the synthesis of accurate small-molecule models has been hampered by the complexity of the cluster.

In the present article, a well-defined trinuclear precursor was utilized to prepare a MnIV3CaO4 cubane toward modeling the complicated active site cluster of the OEC in PSII. The synthesis of this heterometallic complex was facilitated by the nature of the trinucleating ligand, which is based on a triarylbenzene motif appended with pyridine and alcohol donors. Part of the debate regarding the mechanism of O-O bond formation in OEC revolves around the role of Ca2+. Electrochemical comparison reveals that the calcium-containing MnIV3CaO4 cubane reduces at potentials more than 1 V more negative compared to an all-manganese MnIV3MnIIIO4 cluster. These data show that the presence of the non-redox active calcium center in place of manganese facilitates the formation of a species containing more highly oxidized manganese centers at lower potentials.

In selecting this paper for the Sixth RFFBR Paper Award, the Board of directors of the Rebeiz Foundation felt that the described work will greatly benefit other chloroplast researchers, and enhance our knowledge of mechanism of Oxygen evolution in PHotosystem II

A copy of the certificate of recognition is displayed below

rffbrsixthpaperawardfor2011agapiecertificate

Photographs of Theodore Agapie and his Research group are displayed below

rffbrsixthpaperawardfor2011agapieheadandshoulder

Theodore Agapie

Photograph of Theodore Agapie's Research Group

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