Minimum structural requirement for an inhalational anesthetic binding site on a protein target.
The present study makes use of direct photoaffinity labeling and fluorescence and circular dichroism spectroscopy to examine the interaction of the inhalational anesthetic halothane with the uncharged alpha-helical form of poly(L-lysine) over a range of chain lengths. Halothane bound specifically to long chain homopolymers (190 to 1060 residues), reaching a stable stoichiometry of 1 halothane to 160 lysine residues in polymers longer than 300 residues. Halothane bound only non-specifically to an alpha-helical 30 residue polymer and to all of the polymers in their charged, random coil form. The data suggest that halothane binding is a function of supersecondary structure whereby intramolecular helix-helix clusters form in the longer polymers, resulting in the creation of confined hydrophobic domains. Circular dichroism spectroscopy cannot demonstrate changes in poly(L-lysine) secondary structure at any chain length with up to 12 mM halothane, suggesting that extensive hydrogen bond disruption by the anesthetic does not occur.
Johansson
J S
JS
Department of Anesthesiology, University of Pennsylvania Medical Center, Philadelphia, 19104-4283, USA.
Eckenhoff
R G
RG
D000345:Affinity Labels; D018685:Anesthetics, Inhalation / Q000737:chemistry / Q000378:metabolism*; D000817:Anilino Naphthalenesulfonates; D001665:Binding Sites; D002942:Circular Dichroism; D005456:Fluorescent Dyes; D011485:Protein Binding; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence
D000345:Affinity Labels; D018685:Anesthetics, Inhalation; D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; C027132:1-anilino-8-naphthalenesulfonate