Orientation and rotational motions of single molecules by polarized total internal reflection fluorescence microscopy (polTIRFM)

Cold Spring Harb Protoc. 2012 May 1;2012(5):10.1101/pdb.top069344 pdb.top069344. doi: 10.1101/pdb.top069344.

Abstract

In this article, we describe methods to detect the spatial orientation and rotational dynamics of single molecules using polarized total internal reflection fluorescence microscopy (polTIRFM). polTIRFM determines the three-dimensional angular orientation and the extent of wobble of a fluorescent probe bound to the macromolecule of interest. We discuss single-molecule versus ensemble measurements, as well as single-molecule techniques for orientation and rotation, and fluorescent probes for orientation studies. Using calmodulin (CaM) as an example of a target protein, we describe a method for labeling CaM with bifunctional rhodamine (BR). We also describe the physical principles and experimental setup of polTIRFM. We conclude with a brief introduction to assays using polTIRFM to assess the interaction of actin and myosin.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actins / chemistry
  • Actins / metabolism
  • Animals
  • Calmodulin / chemistry*
  • Calmodulin / metabolism
  • Fluorescent Dyes / metabolism
  • Microscopy, Fluorescence / methods*
  • Motion*
  • Myosins / chemistry
  • Myosins / metabolism
  • Protein Binding
  • Rabbits
  • Rhodamines / metabolism
  • Staining and Labeling / methods

Substances

  • Actins
  • Calmodulin
  • Fluorescent Dyes
  • Rhodamines
  • Myosins