Otsuka Remina, Hirata Keisuke, Sasaki Yuta, Lisy James M, Ishiuchi Shun-Ichi, Fujii Masaaki
Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan.
Chemphyschem. 2020 Apr 20;21(8):712-724. doi: 10.1002/cphc.202000033. Epub 2020 Mar 11.
The infrared (IR) spectra of alkali and alkaline earth metal ion complexes with the Ac-Tyr-NHMe (GYG) peptide have been measured by laser photodissociation in a cold ion trap coupled with an electrospray mass spectrometer. The GYG peptide corresponds to a portion of the ion selectivity filter in the KcsA K channel that allows K to pass, but blocks Na even though it has a smaller ionic radius than K . This current study extends a previous investigation on Na and K to the entire set of alkali metaI ions and alkaline earth dications. IR-IR hole-burning (IR dip) spectroscopy has established the coexistence of several conformers of the GYG-metal ion complexes. The structures of the conformers were assigned by comparison between the isomer-selected IR spectra and theoretical IR spectra obtained from quantum chemical calculations. It was found that the structure of the dominant conformer correlates with the ability of the ion to permeate through the K channel.
通过在与电喷雾质谱仪联用的冷离子阱中进行激光光解离，测量了碱金属和碱土金属离子与Ac-Tyr-NHMe（GYG）肽形成的配合物的红外（IR）光谱。GYG肽对应于KcsA钾通道中离子选择性过滤器的一部分，该部分允许钾通过，但即使钠离子的离子半径比钾小，也会阻止其通过。当前的这项研究将先前对钠和钾的研究扩展到了整个碱金属离子和碱土金属二价阳离子组。红外-红外空穴烧蚀（IR dip）光谱法确定了GYG-金属离子配合物的几种构象异构体共存。通过比较异构体选择的红外光谱和从量子化学计算获得的理论红外光谱，确定了构象异构体的结构。研究发现，主要构象异构体的结构与离子透过钾通道的能力相关。
