Water inside the Selectivity Filter of a K⁺ Ion Channel: Structural Heterogeneity, Picosecond Dynamics, and Hydrogen Bonding.

ABSTRACT: Water inside biological ion channels regulates the key properties of these proteins, such as selectivity, ion conductance, and gating. In this article, we measure the picosecond spectral diffusion of amide I vibrations of an isotope-labeled KcsA potassium channel using two-dimensional infrared (2D IR) spectroscopy. By combining waiting time (100-2000 fs) 2D IR measurements of the KcsA channel including ¹³C¹⁸O isotope-labeled Val76 and Gly77 residues with molecular dynamics simulations, we elucidated the site-specific dynamics of water and K⁺ ions inside the selectivity filter of KcsA. We observe inhomogeneous 2D line shapes with extremely slow spectral diffusion. Our simulations quantitatively reproduce the experiments and show that water is the only compon

SUBMITTER: Ryan MJ 

PROVIDER: S-EPMC10797622 | biostudies-literature | 2024 Jan

REPOSITORIES: biostudies-literature