Electrical Field Dependence of Protein Conformation and Channel Function in Lipid Membranes of Different Compositions
Abstract
The objective is to study the effect of electric field on membrane permeability and on the conformation of membrane proteins and channel forming polypeptides to gain insight on their function as channels or as signal transducing receptors. The research has been conducted in model systems, namely lipid monolayers and lipid bilayer membranes. During the second year of our research project we continued with the investigation of the membrane behavior and of the structure of its lipid and protein or polypeptide components under the influence of transmembrane electric fields. The model membranes investigated during this period were lipid monolayers at the mercury electrode/water interface and lipid bilayers with incorporated channel forming polypeptides alamethicin and melittin. The spread lipid monolayers were transferred after their interaction with the polypeptide in the aqueous solution, from the air/ water to the mercury/water interface. Their properties were then inferred from their capacitance and ionic permeability at different electrode potentials. Ionic permeability of unilamellar vesicles upon interaction with the channel forming polypeptides and proteins was determined with and without applied diffusion potential. The change in conformation of specific membrane components with applied electric field was studied by circular dichrosim (CD) and Fourier transform infrared (FTIR) measurements. Transmembrane potentials induced were either diffusion potentials (K+ gradient valinomycin) in non-leaky membranes or Donnan potential when high channel concentrations made the membranes leaky to small ions. Keywords: Alamethicin; Melittin.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1989
- Accession Number
- ADA210236
Entities
People
- Israel R. Miller
Organizations
- Weizmann Institute of Science