Analysis of anisotropy decays in terms of correlation time distributions, measured by frequency-domain fluorometry.
We describe the theory and practical aspects of analyzing fluorescence anisotropy decays in terms of correlation times distributions. In our model the rotational motions of the fluorophores were described using Gaussian or Lorentzian distributions of the correlation times. The theory is presented both for time and frequency-domain measurements, although the simulations and measurements are focused on the frequency-domain measurements of the anisotropy decays. Analysis of simulated data is presented to illustrate the nature of the data and the resolution which can be expected with presently available frequency-domain measurements. Additionally, we describe experimental data for samples where one can reasonably expect a single exponential and/or discrete multi-exponential correlation time distributions, and for samples where the anisotropy decay might be expected to display a distribution of correlation times. These samples include small single tryptophan peptides in propylene glycol, the single tryptophan residue in S. Nuclease, and the single tryptophan residue in the native and partially unfolded states of ribonuclease T1.
Gryczynski
I
I
University of Maryland School of Medicine, Department of Biological Chemistry, Baltimore 21201.
Johnson
M L
ML
Lakowicz
J R
JR
D000595:Amino Acid Sequence; D003198:Computer Simulation; D005454:Fluorescence Polarization / Q000379:methods*; D005470:Fluorometry / Q000379:methods; D006146:Guanidines; D008432:Mathematical Computing; D008836:Micrococcal Nuclease / Q000032:analysis; D008969:Molecular Sequence Data; D010455:Peptides / Q000032:analysis; D006163:Ribonuclease T1 / Q000032:analysis; D013696:Temperature; D013997:Time Factors; D014364:Tryptophan / Q000032:analysis
D006146:Guanidines; D010455:Peptides; D014364:Tryptophan; D006163:Ribonuclease T1; D008836:Micrococcal Nuclease