title: Intrinsic reaction-cycle time scale of Na+,K+-ATPase manifests itself in the lipid-protein interactions of nonequilibrium membranes.
abstract: Interaction between integral membrane proteins and the lipid-bilayer component of biological membranes is expected to mutually influence the proteins and the membrane. We present quantitative evidence of a manifestation of the lipid-protein interactions in liposomal membranes, reconstituted with actively pumping Na(+),K(+)-ATPase, in terms of nonequilibrium shape fluctuations that contain a relaxation time, τ, which is robust and independent of the specific fluctuation modes of the membrane. In the case of pumping Na(+)-ions, analysis of the flicker-noise temporal correlation spectrum of the liposomes leads to τ ~/= 0.5 s, comparing favorably with an intrinsic reaction-cycle time of about 0.4 s from enzymology.
authors.affiliation: Department of Physics, Chemistry and Pharmacy, MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, 5230 Odense M, Denmark.
authors.forename: Hélène
authors.initials: H
authors.lastname: Bouvrais
authors.forename: Flemming
authors.initials: F
authors.lastname: Cornelius
authors.forename: John H
authors.initials: JH
authors.lastname: Ipsen
authors.forename: Ole G
authors.initials: OG
authors.lastname: Mouritsen
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002784:Cholesterol / Q000737:chemistry; D004789:Enzyme Activation; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes / Q000378:metabolism*; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D011485:Protein Binding; D012754:Sharks; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors
chemical_list: D008055:Lipids; D008081:Liposomes; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; C042511:1,2-dioleoylphosphatidylserine; D000255:Adenosine Triphosphate; D002784:Cholesterol; D000254:Sodium-Potassium-Exchanging ATPase; C017251:1,2-oleoylphosphatidylcholine