Real-time dipole orientational imaging as a probe of ligand-protein interactions

Osborne, Mark (2005) Real-time dipole orientational imaging as a probe of ligand-protein interactions. Journal of Physical Chemistry B, 109 (38). pp. 18153-18161. ISSN 15206106

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Single-molecule orientational imaging using total internal reflection fluorescence microscopy has been employed to investigate the dynamics of a protein-ligand system. Emission patterns from single tetramethylrhodamine (TMR)-biocytin molecules bound to streptavidin show that the TMR dipole adopts a limited number of favored orientations. The angular trajectories of individual dipoles exhibit remarkably similar patterns that are characteristic of single TMR molecules interacting with a relatively homogeneous population of nanoenvironments. Analysis of the polar and azimuthal angle distributions reveals a tendency for the dipole to assume three primary and two secondary orientations. Autocorrelation analysis of the dipole trajectories shows a predominantly bimodal behavior in the reorientation rates with the slow and fast components corresponding to the primary and secondary orientations, respectively. A number of mechanisms by which the observed orientations might be stabilized have been considered, in particular specific interactions between the zwitterionic TMR probe and charged residues on the streptavidin surface. Variations in the reorientation rates have been discussed in terms of local thermal fluctuations in the protein.

Item Type: Article
Additional Information: First demonstration of single molecule dipole imaging at video-rate with a biological application to ligand-protein interaction dynamics. Experimental design, construction, imaging, simulation and data analysis was executed by MAO who is also sole and corresponding author.
Schools and Departments: School of Life Sciences > Chemistry
Depositing User: Mark Osborne
Date Deposited: 06 Feb 2012 20:18
Last Modified: 31 May 2012 16:20
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