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千葉 薫*; 松井 拓郎*; 茶竹 俊行*; 大原 高志; 田中 伊知朗*; 油谷 克英*; 新村 信雄*
Protein Science, 32(10), p.e4765_1 - e4765_13, 2023/10
被引用回数：0 パーセンタイル：0(Biochemistry & Molecular Biology)In structural biology, peptide bonds, fundamental linkages between hundreds of amino acids, of which a protein molecule is composed, have been commonly treated as a plane structure just as Linus Pauling et al. proposed. In this paper, a site-specific peptide bond relaxation mechanism by deuterons whose localization has been suggested by neutron crystallography is proposed. A comprehensive study using X-ray and neutron diffraction and 
N chemical shifts of individual amide nitrogen atoms within the same peptide bond strongly suggests the relaxation of the electronic resonance structure because of site-specific modulation by protons/deuterons localized on the electron orbital of the carbonyl oxygen.
大原 高志; 中尾 朗子*; 宗像 孝司*; 茂吉 武人*; 花島 隆泰*; 鬼柳 亮嗣; 細谷 孝明*; 原 嘉昭*
no journal, ,
2-(2'-hydroxyphenyl)benzimidazole (HPBI) has an intramolecular O-H...N hydrogen bond and shows photo-induced excited-state intramolecular proton transfer, from the enol form to the keto form. Recently, we found that a novel polymorph (gamma-form) of HPBI crystal. We carried out single-crystal neutron diffraction measurements of the gamma-form at 90K and 298K by using SENJU single-crystal diffractometer at J-PARC MLF to observe the temperature-induced proton transfer in the intramolecular hydrogen bond from the enol-form (O-H...N) to the keto-form (O...H-N). In the result, negative density of atomic scattering length which comes from the proton of the keto-form was observed at 298K even though no keto-form was observed at 90K. In the gamma-form, HPBI molecule forms stronger intermolecular N-H...O hydrogen bond than that in the known polymorph. This hydrogen-bond possibly contributes to lowering the potential barrier between the enol and keto-forms.
