Surface and Molecular Forces Governing the Transport of Ions Across Electrically Excitable Membranes
Abstract
The aims of this project are: to measure the internal aqueous volume changes during the gating of ionic channels by trans-membrane voltage; to distinguish between various molecular structural models of channel gating; to connect channel gating and specificity with measurements of intermolecular forces. To this end, we have used osmotic stress to determine that a significant fraction of the internal aqueous volume is lost upon closure of two very different channels -- the anion channel from the outer membrane of mitochondria, and the potassium channel from the squid giant axon. The structural rearrangements that probably accompany such closure require that one recognize the likely motion of channel protein and the energetic importance of channel volume hydration. Protein motion immediately implicates mechanical properties of membrane lipids and proteins as part of the gating process; cavity hydration immediately requires recognition of the specific action of transversing ions on the energy of opening. Keywords: Ionic channels, Voltage gating, Intermolecular forces, Surface potentials, Surface energies, Molecular assembly, Ligand binding, Ion specificity.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 15, 1988
- Accession Number
- ADA197659
Entities
People
- V. A. Parsegian
Organizations
- National Institutes of Health