K(+) preference at the NaK channel entrance revealed by fluorescence lifetime and anisotropy analysis of site-specifically incorporated (7-hydroxycoumarin-4-yl)ethylglycine

Chem Commun (Camb). 2015 Nov 14;51(88):15971-4. doi: 10.1039/c5cc06124e. Epub 2015 Sep 18.

Abstract

The fluorescent unnatural amino acid, (7-hydroxycoumarin-4-yl)ethylglycine (HC), was site-specifically incorporated at the Phe69 site, close to the entrance of the selectivity filter of the NaK channel. Decreased fluorescence lifetime and elevated time-resolved anisotropy of NaK-F69HC in buffers with high K(+)/Na(+) molar ratios indicated the K(+) preference at the entrance of the NaK channel, consistent with previous crystal structure results of the NaK channel.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus cereus
  • Bacterial Proteins / physiology*
  • Bacterial Proteins / ultrastructure
  • Fluorescence Polarization*
  • Glycine / analogs & derivatives*
  • Glycine / chemistry
  • Glycine / genetics
  • Mutagenesis, Site-Directed
  • Potassium / physiology*
  • Potassium Channels / physiology*
  • Potassium Channels / ultrastructure
  • Umbelliferones / chemistry*

Substances

  • (7-hydroxycoumarin-4-yl) ethylglycine
  • Bacterial Proteins
  • Potassium Channels
  • Umbelliferones
  • prokaryotic potassium channel
  • Potassium
  • Glycine