Thermodynamic properties of single ion channel formation: gramicidin

Thermodynamic properties of single ion channel formation: gramicidin
Engineering Village 2
? 2006 Elsevier Inc
Accession number: 8334234

Title: Thermodynamic properties of single ion channel formation: gramicidin

Authors: Davis, R.W.1 ; Patrick, E.L.; Meyer, L.A.; Ortiz, T.P.; Marshall, J.A.; Keller, D.J.; Brozik, S.M.; Brozik, J.A.

Author affiliation: 1 Dept. of Chem., New Mexico Univ., Albuquerque, NM, USA

Serial title: Journal of Physical Chemistry B

Abbreviated serial title: J. Phys. Chem. B (USA)

Volume: 108

Issue: 39

Publication date: 30 Sept. 2004

Pages: 15364-9

Language: English

ISSN: 1089-5647


Document type: Journal article (JA)

Publisher: ACS

Country of publication: USA

Material Identity Number: G111-2004-041

Abstract: Single molecule fluorescence imaging has been used to unequivocally differentiate between rhodamine-6G labeled gramicidin monomeric subunits and channel-forming dimers. Absolute identification of individual particles was achieved by accounting for both particle diffusion and intensity, with dimer intensity being twice that of the monomers. In accordance with current diffusion models of proteins in bilayer membranes, we observed dimers to diffuse more slowly through the bilayer than the monomers and have reported diffusion coefficients of 1.2?10-8 and 3.5?10-8 cm2/s for the dimers and monomers, respectively. By correlating the diffusion data with measured fluorescence intensities of the tracked particles, it was possible to determine the distribution of monomers and dimers within the bilayer at various temperatures. The results allow complete characterization of the thermodynamic properties of dimer formation, 2G1?G2, necessary for channel function. Reported are the temperature-dependent equilibrium constants, ?H˚Reaction, ?G˚Reaction, and ?S˚Reaction, for dimer formation in an artificial lipid membrane that has a thickness (30 ?) which is on the same order as the length of the gramicidin channel (26 ?). These experiments compliment and expand single molecule fluorescence methods needed to understand the complexities of ion channel structure/function relationships

Number of references: 35

Inspec controlled terms: biodiffusion - bioelectric phenomena - biological techniques - biomembrane transport - chemical equilibrium - fluorescence - lipid bilayers - macromolecules - molecular biophysics - proteins - spectral line intensity - thermodynamic properties

Uncontrolled terms: thermodynamic properties - single ion channel formation - single molecule fluorescence imaging - rhodamine-6G labeled gramicidin monomeric subunits - particle diffusion - particle intensity - dimer intensity - proteins - bilayer membranes - diffusion coefficients - tracked particle fluorescence intensities - dimer formation - channel function - temperature-dependent equilibrium constants - artificial lipid membrane - ion channel structure-function relationships - 30 ? - 26 ?

Inspec classification codes: A8725D Biological transport; cellular and subcellular transmembrane physics - A8260H Chemical equilibria and equilibrium constants - A8720 Membrane biophysics - A8715B Biomolecular structure, configuration, conformation, and active sites - A3620C Macromolecular conformation (statistics and dynamics) - A3350D Molecular fluorescence and phosphorescence spectra - A8715M Interactions with radiations at the biomolecular level - A8728 Bioelectricity

Numerical data indexing: size 3.0E-09 m;size 2.6E-09 m

Treatment: Experimental (EXP)

Discipline: Physics (A)

DOI: 10.1021/jp049686y

Database: Inspec

Copyright 2005, IEE
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