Time-dependent phosphorescence anisotropy measurements of the slow rotational motions of proteins in viscous solution
✍ Scribed by Giovanni B. Strambini; William C. Galley
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1980
- Tongue
- English
- Weight
- 621 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
A method of monitoring slow rotational motions of proteins from the decay of the intrinsic phosphorescence is described. The phosphorescence is excited with a 10‐μsec pulse of vertically polarized light from an air gap lamp, and the anisotropy was computed as a function of time from the simultaneously detected vertically and horizontally polarized components of the emission. The approach is illustrated with time‐dependent measurements of the anisotropy of the tryptophan phosphorescence of Staphylococcus aureus nuclease, bovine carbonic anhydrase, and liver alcohol dehydrogenase in glycerol‐phosphate buffer between −90 and −70°C. The temperature‐ and molecular‐weight dependence of the exponential decays in the anisotropy indicate that overall rotation of the proteins is at the origin of the depolarization. The potential of the approach as a probe of the slow rotational motions of proteins in membranes and other macromolecular complexes is stressed.