Terbium luminescence-lifetime heterogeneity and protein equilibrium conformational dynamics.
The fluorescence decay of the rare earth terbium when bound to the protein calmodulin changes from a simple exponential decay to a complex nonexponential decay as the temperature is lowered below 200 K. We have fit the observed decay curves by assuming that the terbium emission is a forced electric dipole transition and proteins have a distribution of continuous conformational states. Quantitative fits to the data indicate that the root-mean-square configurational deviation of the atoms surrounding the terbium ion is 0.2 A, in good agreement with other measurements. We further point out that because the protein seems to undergo a glass transition yet retains configurational order at room temperature, the proper name for the physical state of a protein at room temperature is the rubber-like state.
Austin
R H
RH
Stein
D L
DL
Wang
J
J
D002147:Calmodulin; D008163:Luminescent Measurements; D011487:Protein Conformation; D013696:Temperature; D013725:Terbium
D002147:Calmodulin; D013725:Terbium