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Imaging the Molecular Dimensions and Oligomerization of Proteins at Liquid/Solid Interfaces
The Journal of Physical Chemistry B (1998)
  • Mark J Waner, John Carroll University
  • Martha Gilchrist
  • Melvin Schindler
  • Marcos Dantus

Individual Concanavalin A (ConA) molecules have been imaged at the liquid/solid interface with an atomic force microscope (AFM). Three-dimensional sizing with very high resolution (<5 Å) has been obtained by a novel approach based on height distributions, which avoids the tip convolution effects which normally affect scanning probe microscopy techniques. Each height measurement correlates to a particular molecular orientation on the surface. A large number of such measurements provide a statistical ensemble of orientations. The complete height distribution reflects the three-dimensional size of the protein sample and hence its tertiary and quaternary structure. A surface adsorption and orientation model, based on a minimization of surface adsorption energy, is proposed. This model is in good agreement with the observed height distribution of Con A molecules at the liquid/solid interface. Analysis of Con A and succinylated Con A molecules on mica demonstrates that Con A dimers are the prevalent species at the liquid/solid interface. This is in contrast to the tetrameric organization of Con A normally observed in solution. The new possibilities opened by height distribution analysis on the physical characterization of biomolecules at interfaces are also discussed.

Publication Date
February 26, 1998
Citation Information
Mark J Waner, Martha Gilchrist, Melvin Schindler and Marcos Dantus. "Imaging the Molecular Dimensions and Oligomerization of Proteins at Liquid/Solid Interfaces" The Journal of Physical Chemistry B Vol. 102 Iss. 9 (1998)
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