Neutron structure analysis of high-potential iron-sulfur protein

Hirano, Yu; Tamada, Taro; Kurihara, Kazuo; Kusaka, Katsuhiro*; Miki, Kunio*

High-potential iron-sulfur protein (HiPIP) possesses a 4Fe-4S cluster as a cofactor that shows 2+/3+ redox states. HiPIP is a soluble electron carrier protein that works in the photosynthetic electron transfer chain of purple photosynthetic bacteria. We have determined the neutron crystal structure of HiPIP at high resolution to obtain structure information including hydrogen atoms. Neutron diffraction experiment was performed at J-PARC, and the diffraction data set was obtained at 1.1 resolution that is the highest resolution in the protein neutron diffraction data. To perform X-ray and neutron joint refinement, we also collected X-ray diffraction data at Photon Factory, and the diffraction data set was obtained at 0.66 resolution.