Tryptophan dynamics of the FK506 binding protein: time-resolved fluorescence and simulations.
AUTOR(ES)
Silva, N D
RESUMO
The FK506-binding protein (FKBP12) is important in the immunosuppressant action of FK506 and rapamycin. We have investigated Trp side chain dynamics in FKBP12, with and without a bound immunosuppressant, by measuring the Trp time-resolved fluorescence anisotropy decay r(t). The r(t) for W59 in aqueous uncomplexed FKBP12 at 20 degrees C is well described by a single exponential with a recovered initial anisotropy, r(eff)o, of 0.192 and an overall rotational correlation time for the protein, phi p, of 4.7 ns; r(eff)o = 0.214 and phi p = 4.2 ns for the FKBP12/FK506 complex. Using an expression for the order parameter squared, namely S2 = r(eff)o/rTo, where rTo is the vitrified steady-state excitation anisotropy, we recovered an S2 of 0.75 for W59 fluorescence in uncomplexed FKBP12 and S2 approximately equal to 1 in the FKBP12/FK506 complex. Results obtained for the FKBP12/rapamycin complex are similar to those found for the FKBP12/FK506 complex. Minimum perturbation mapping simulations were performed on the free and complexed forms of FKBP12 and the results were generally in agreement with the experimental data.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1225042Documentos Relacionados
- Time-resolved fluorescence of the single tryptophan of Bacillus stearothermophilus phosphofructokinase.
- Heat capacity changes and hydrophobic interactions in the binding of FK506 and rapamycin to the FK506 binding protein.
- Picosecond time-resolved absorption and fluorescence dynamics in the artificial bacteriorhodopsin pigment BR6.11.
- Time-resolved protein fluorescence studies of intermediates in the photochemical cycle of bacteriorhodopsin.
- Time-resolved circularly polarized protein phosphorescence.