Microinjection in combination with microfluorimetry to study proton diffusion along phospholipid membranes.
Proton diffusion along the surface of a planar bilayer lipid membrane was measured by means of acid/base injection with a micropipette and recording of the kinetics of fluorescence changes of fluorescein-labelled lipid on the surface. The dimensionality of the process was assayed by fitting the kinetic curves with two-dimensional (2D) or three-dimensional (3D) diffusion equations. In agreement with Serowy et al. (Biophys J 84:1031-1037, 2003), lateral proton diffusion proceeded via bulk phase by means of buffer molecules as proton carriers (D = 600 microm2/s) under the conditions of 1 mM buffer in the solution. Introduction of proton binding sites on the membrane surface led to the appearance of a considerable contribution of two-dimensional proton diffusion on the membrane surface with D = 1,100 mum(2)/s. The system described can be used to study the dependence of the proton diffusion rate on the phospholipid and protein composition of the membrane.
Antonenko
Yuri N
YN
A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119992, Russia. antonen@genebee.msu.ru
Pohl
Peter
P
D004058:Diffusion; D005434:Flow Cytometry / Q000379:methods*; D008051:Lipid Bilayers / Q000737:chemistry*; D008567:Membranes, Artificial; D008845:Microinjections / Q000379:methods*; D010743:Phospholipids / Q000737:chemistry*; D011522:Protons
D008051:Lipid Bilayers; D008567:Membranes, Artificial; D010743:Phospholipids; D011522:Protons