Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan.
J Phys Chem A. 2024 Aug 1;128(30):6208-6215. doi: 10.1021/acs.jpca.4c03178. Epub 2024 Jul 23.
The electronic and vibrational cryogenic ion spectroscopy of protonated tryptophan (TrpH) and dopamine (DAH) complexed with methanol has been recorded. These two biological chromophores exhibit ultrafast photochemistry due to excited-state proton transfer (ESPT). We have established the relationship between the structure of the complexes and their photodynamics and compared them with recent results obtained in hydrated complexes. For TrpH, there is no substantial change between methanol and water complexes; ESPT is hindered by a single solvent molecule. In the DAH(MeOH) complex, the most stable conformer adopts a structure that prevents the direct interaction of the ammonium group of the side chain with the catechol ring, thus blocking the ESPT reaction. Such a ring structure is indeed a very minor populated conformer in the single-hydrated complex. The change in conformal stability between water and methanol clusters is due to a weak CH-π attractive interaction of the methyl group of methanol with the catechol.
已记录下与甲醇配位的质子化色氨酸（TrpH）和多巴胺（DAH）的电子和振动低温离子光谱。由于激发态质子转移（ESPT），这两种生物生色团表现出超快光化学。我们已经确定了复合物的结构与其光动力之间的关系，并将其与最近在水合复合物中获得的结果进行了比较。对于 TrpH，甲醇和水复合物之间没有实质性变化；ESPT 受到单个溶剂分子的阻碍。在 DAH（MeOH）复合物中，最稳定的构象采用一种结构，阻止侧链铵基团与儿茶酚环的直接相互作用，从而阻止 ESPT 反应。这种环结构实际上是单水合复合物中非常少有的构象。水和甲醇簇之间构象稳定性的变化是由于甲醇的甲基与儿茶酚之间的弱 CH-π 吸引相互作用。
