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.
The front cover artwork is provided by Takashi Tsujino (Science Graphics Co., Ltd.) . The image shows the efficacy of a bottom‐up approach to ion selectivity of K+ channels. The GYG‐K+ complex, which replicates the local portion of K+ channels, has three conformations with an equivalent distribution. Read the full text of the Article at 10.1002/cphc.202000033.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.