Determination of hydrogen positions of photoactive yellow protein

山口 繁生*; 上久保 裕生*; 栗原 和男; 清水 哲哉*; 山崎 洋一*; 黒木 良太; 新村 信雄*; 片岡 幹雄*

no journal, , 

Hydrogen atoms play important roles for many biochemical reactions. In the case of photoactive yellow protein (PYP), protonation/deprotonation reactions on amino acid residues and the following rearrangements in the hydrogen bond network are proposed to be closely related with the conformational changes. To understand the molecular mechanism, it is essential to determine the positions of hydrogen atoms. Neutron crystallographic and high resolution X-ray crystallographic studies are well known to be useful for observation of hydrogen atoms. We could obtain a fairly large and high quality crystal of PYP (2.89 0.85 0.79 mm) which gave X-ray diffraction spots up to 0.7. The high-resolution structural analysis clarified previously unknown hydrogen bonding network related with the tertiary structural change. To confirm the hydrogen positions, we are also carrying out neutron diffraction experiments with the obtained crystal.