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제124회 대한화학회 학술발표회, 총회 및 기기전시회 Interpretation of Hofmeister series: Formation of an amide tautomer by divalent cations

2019년 8월 22일 15시 57분 12초
PHYS.P-192 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
10월 17일 (목요일) 11:00~12:30
Physical Chemistry
저자 및
Hyejin Kwon, Yung sam Kim*, Jin Gyu Seol
Department of Chemistry, Ulsan National Institute of Science and Technology, Korea
Ion-specific effects on peptides and proteins are crucial to the biomolecular structure. Compared with the significant role of anions, the subtle effects of cations on proteins have not been clearly understood. Importantly, divalent cations like Ca2+ and Mg2+ are known to be crucial to biological functions. Herein, we report that the direct binding of the divalent cations to the amide oxygen in aqueous solution triggers an amide‒iminolate tautomer equilibrium. For N-methyl acetamaide (NMA) dissolved in aqueous 5M CaCl2 solution, the formation of an amide tautomer is strongly supported by two-dimensional infrared (2D IR) spectroscopy of the amide vibration and molecular dynamics (MD) simulations of molecular phenomenon. The interconversion timescale (~17 ps) between the tautomers confirms that Ca2+ forms direct contact with the amide O intermittently. These results confirm the arrest of an unusual amide tautomer by the divalent cations and provide an explanation for the shift in the aggregation pathway of neurotoxic peptides in the presence of divalent cations.