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Updated: Jun 10, 2026

Monitoring Protein Adsorption with Solid-state Nanopores
Published on: December 2, 2011
Effect of surface charge distribution on the adsorption orientation of proteins to lipid monolayers
Sebastian Tiemeyer1, Michael Paulus, Metin Tolan
1Fakultät Physik/DELTA, Technische Universität Dortmund, Maria-Goeppert-Mayer-Str. 2, D-44221 Dortmund, Germany. sebastian.tiemeyer@tu-dortmund.de
Abstract:
The adsorption orientation of the proteins lysozyme and ribonuclease A (RNase A) to a neutral 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and a negatively charged stearic acid lipid film was investigated by means of X-ray reflectivity. Both proteins adsorbed to the negatively charged lipid monolayer, whereas at the neutral monolayer, no adsorption was observed. For acquiring comprehensive information on the proteins' adsorption, X-ray reflectivity data were combined with electron densities obtained from crystallographic data. With this method, it is possible to determine the orientation of adsorbed proteins in solution underneath lipid monolayers. While RNase A specifically coupled with its positively charged active site to the negatively charged lipid monolayer, lysozyme prefers an orientation with its long axis parallel to the Langmuir film. In comparison to the electrostatic maps of the proteins, our results can be explained by the discriminative surface charge distribution of lysozyme and RNase A.
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