Alkali and Alkaline Earth Metal Ions Complexes with a Partial Peptide of the Selectivity Filter in K+ Channels Studied by a Cold Ion Trap Infrared Spectroscopy
Alkali and Alkaline Earth Metal Ions Complexes with a Partial Peptide of the Selectivity Filter in K+ Channels Studied by a Cold Ion Trap Infrared Spectroscopy
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DOI：
10.1002/cphc.202000033
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发表时间：
2020-03-11
期刊：
影响因子：
2.9
通讯作者：
Fujii, Masaaki
中科院分区：
文献类型：
--
作者：
Otsuka, Remina;Hirata, Keisuke;Fujii, Masaaki
在冷离子阱电喷雾质谱仪上用激光光解法测定了碱金属和碱土金属离子与Ac-Tyr-NHMe（GYG）肽配合物的红外光谱。GYG肽对应于KcsA K+通道中的离子选择性过滤器的一部分，其允许K+通过，但阻止Na+，即使其具有比K+更小的离子半径。本研究将以前对Na+和K+的研究扩展到整个碱金属离子和碱土金属离子。红外-红外烧孔（IR 2浸）光谱已经建立了共存的几种构象的GYG-金属离子络合物。通过比较异构体选择的红外光谱和量子化学计算得到的理论红外光谱，对构象异构体的结构进行了归属。据发现，占主导地位的构象的结构与离子渗透通过K+通道的能力。
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 (IR2 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.