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Measuring the Orientation and Re-Orientation Dynamics of Single Molecules



K D. Weston, Lori S. Goldner


Single molecule fluorescence techniques for the study of macromolecular motion and conformational dynamics are useful for understanding the mechanisms of protein action (i.e., protein catalysts, protein pumps, and motor proteins) and protein folding. Molecular motion is often inferred from fluctuations in the fluorescence intensity, spectrum, or lifetime of a single molecule. Additional information can be acquired by monitoring the orientation of the excitation and/or emission dipole of a fluorophore. Here we report on the direct observation of molecular motion from time-resolved measurements of absorption dipole orientation on single fluorophores embedded in polymeric matrices. Using a polarizationmodulation technique, we record both the position and dipole orientation of all molecules in an image. For each detected molecule, the orientation as a function of time is also monitored on a millisecond time-scale. These studies reveal large and frequent dipole re-orientations for dye molecules in a variety of polymer matrices. Further applications of this technique to study the rotational dynamics of dye molecules in biomimetic films, in porous media, and linked to proteins will be discussed.
Proceedings Title
Sigma Xi Post Doctoral Poster Presentations, 2000 | | |
Conference Dates
February 17-18, 2000
Conference Title
Sigma Xi Web Page


fluorophore, macromolecular motion, polymeric matrices, protein action, protein folding, single molecule fluorescence, single molecules


Weston, K. and Goldner, L. (2000), Measuring the Orientation and Re-Orientation Dynamics of Single Molecules, Sigma Xi Post Doctoral Poster Presentations, 2000 | | | (Accessed June 22, 2024)


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Created February 1, 2000, Updated February 17, 2017