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A model membrane protein for binding volatile anesthetics.

TitleA model membrane protein for binding volatile anesthetics.
Publication TypeJournal Article
Year of Publication2004
AuthorsYe, S, Strzalka, J, Churbanova, IY, Zheng, S, Johansson, JS, J Blasie, K
JournalBiophys J
Volume87
Issue6
Pagination4065-74
Date Published2004 Dec
ISSN0006-3495
KeywordsAmino Acid Sequence, Anesthetics, Inhalation, Binding Sites, Drug Design, Halothane, Ion Channels, Membrane Proteins, Molecular Sequence Data, Protein Binding, Protein Conformation, Protein Structure, Secondary, Solubility
Abstract

Earlier work demonstrated that a water-soluble four-helix bundle protein designed with a cavity in its nonpolar core is capable of binding the volatile anesthetic halothane with near-physiological affinity (0.7 mM Kd). To create a more relevant, model membrane protein receptor for studying the physicochemical specificity of anesthetic binding, we have synthesized a new protein that builds on the anesthetic-binding, hydrophilic four-helix bundle and incorporates a hydrophobic domain capable of ion-channel activity, resulting in an amphiphilic four-helix bundle that forms stable monolayers at the air/water interface. The affinity of the cavity within the core of the bundle for volatile anesthetic binding is decreased by a factor of 4-3.1 mM Kd as compared to its water-soluble counterpart. Nevertheless, the absence of the cavity within the otherwise identical amphiphilic peptide significantly decreases its affinity for halothane similar to its water-soluble counterpart. Specular x-ray reflectivity shows that the amphiphilic protein orients vectorially in Langmuir monolayers at higher surface pressure with its long axis perpendicular to the interface, and that it possesses a length consistent with its design. This provides a successful starting template for probing the nature of the anesthetic-peptide interaction, as well as a potential model system in structure/function correlation for understanding the anesthetic binding mechanism.

DOI10.1529/biophysj.104.051045
Alternate JournalBiophys. J.
PubMed ID15465862
PubMed Central IDPMC1304915
Grant ListP01 GM055876 / GM / NIGMS NIH HHS / United States
GM55876 / GM / NIGMS NIH HHS / United States