Regensburg 2004 – scientific programme

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AKB: Biologische Physik

AKB 50: Poster Session "Biological Physics"

AKB 50.112: Poster

Friday, March 12, 2004, 10:30–13:00, B

Electrophoretic Accumulation of Membrane Bound Proteins on Polymer Supports — •Joachim Hermann¹, Markus Fischer², Steven Boxer³, and Motomu Tanaka¹ — ¹Physik Department, Lehrstuhl f"ur Biophysik E22, TU M"unchen, James-Franck-Str., D-85748 Garching — ²Fakult"at f"ur Chemie, TU M"unchen, James-Franck-Str., D-85748 Garching — ³Department of Chemistry, Stanford University, CA 94305-5080, USA

The presented work deals with the local biofunctionalization of solid surfaces by means of electrophoretic accumulation of genetically engineered recombinant proteins docking onto membranes deposited on polymer supports. His-tagged fluorescent proteins (GFP and DsRed) were firstly coupled homogeneously to lipid monolayers doped with chelator (NTA) lipids, then a DC electric field was applied for accumulation of the proteins. The resulting concentration gradient of proteins at equilibrium could empirically be analyzed by a simple differential equation. As a result, the mean velocities and mobilties of the two proteins were obtained.

The proteins on the membrane surface experienced not only electrophoretic forces but also electroosmosis in the opposite direction. The counter balance between these two opposing forces was further studied by shifting the surface charge densities, namely, the difference in zeta potentials between the membrane and the proteins. In fact, incorporation of oppositely charged lipids into the membrane led to larger mean velocities for both proteins, which supports the proposed scenario semi-quantitatively.