title: Changes in ion channel geometry resolved to sub-ångström precision via single molecule mass spectrometry.
abstract: The ion channel formed by Staphylococcus aureus alpha-hemolysin switches between multiple open conducting states. We describe a method for precisely estimating the changes in the ion channel geometry that correspond to these different states. Experimentally, we observed that the permeability of a single channel to differently sized poly(ethylene glycol) molecules depends on the magnitude of the open state conductance. A simple theory is proposed for determining changes in channel length of 4.2% and in cross-sectional area of -0.4%.
authors.affiliation: Semiconductor Electronics Division, Electronics and Electrical Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors.forename: Joseph W F
authors.initials: JW
authors.lastname: Robertson
authors.forename: John J
authors.initials: JJ
authors.lastname: Kasianowicz
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Reiner
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry / Q000648:ultrastructure; D013058:Mass Spectrometry / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D016062:Porosity; D011487:Protein Conformation
chemical_list: D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D007473:Ion Channels