High-resolution neutron structure studies of high-potential iron-sulfur protein

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

Information about hydrogen atoms are important for understanding both structure and function of proteins. The structure of hydrogen atoms in proteins has been discussed based on the ideal values of bond lengths and angles obtained from structures of small molecules. A huge contribution to the protein science will be made by the structure information of hydrogen atoms without restraints of the ideal values. Hydrogen atoms are easily detected in neutron crystal structures because neutrons have a strong diffraction power compared to other atoms in proteins. In this study, we have determined high-resolution neutron structure of the high-potential iron-sulfur protein (HiPIP). The neutron diffraction experiment was performed at the BL03 (iBIX) beamline of J-PARC/MLF. We have obtained the diffraction data set at 1.1-resolution that is the highest resolution data in protein neutron studies. The protonation states of amino acid residues at the surface of HiPIP have been observed after structure refinement. In addition, many deviations from the ideal values were observed in the distances and angles involved in hydrogen atoms.