| 研究実績の概要 |
The proposed research is progressing well and the current results are described in two parts as follows.(1) Capturing initial intermediates of a CO release reaction within a protein crystal: We Immobilized Mn(CO)3 as a light-induced CO release reaction center inside the Lysozyme microcrystals and studied the light reactions by TR-SFX with varying time and light dose. We found that Mn(CO)3 form an octahedral geometry with two additional water molecules. At the initial stage of reaction, the axial CO released first and we successfully captured the Mn(CO)2 intermediate species. With increasing delay time up to 1ms, we observed the complete release of Mn(CO) unit from the protein. During such chemical reaction, we determined the conformational changes in the surrounding Arg14 residue. Overall, the work is about to finish and we are applying this methodology to new reaction systems. such as gold nanocluster formation etc.(2) Observing gold nanocluster formation within the symmetric channel of a ferritin cage: In this research, we are studying to explore the mechanism of gold cluster formation in protein cavity. At first, we immobilized the Au atoms in the ferritin cage and determined thepositions of Au atoms in the protein structure. Then, we optimized the photoreduction of Au atoms to see movements of Au atoms along with side chain conformational changes during the formation of the nanocluster by usual X-ray crystallography. In the next plan, we will apply TR-SFX method to study the intermediates in short intervals to understand the detail mechanism.
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