Ultra-high resolution structure of high-potential iron-sulfur protein

Hirano, Yu; Takeda, Kazuki*; Kurihara, Kazuo; Tamada, Taro; Miki, Kunio*

It is important for understanding the electron transfer reaction to include the information about valence shell electrons and hydrogen atoms into crystal structure refinement. Recently, we have successfully collected 0.48 resolution data of high-potential iron-sulfur protein (HiPIP) in BL41XU beamline of SPring-8. We performed multipolar refinement with the program to consider valence shell electrons in the structure refinement of HiPIP. After multipolar refinement, the deformation map clearly displays the distribution of valence shell electrons such as lone-pair electrons of carbonyl oxygen atoms, bonding electrons in aromatic rings, and -orbital electrons of Fe atoms in the FeS cluster. In addition, we performed preliminary neutron diffraction experiment at iBIX beamline of Japan Proton Accelerator Research Complex (J-PARC) and observed diffraction spots up to 1.17 resolution using HiPIP crystal with the size of 2.3 mm.