T. Abouaiad et al., DIELECTRIC-RELAXATION OF AQUEOUS-SOLUTIONS OF RIBONUCLEASE-A IN THE ABSENCE AND PRESENCE OF UREA, Berichte der Bunsengesellschaft fur Physikalische Chemie, 101(12), 1997, pp. 1921-1927
Citations number
29
Journal title
Berichte der Bunsengesellschaft fur Physikalische Chemie
The dielectric spectra of aqueous solutions of ribonuclease A (RNase)
have been measured in the frequency domain over the whole absorption r
egion between 2 MHz and 72 GHz at 20 degrees C in two solvents, pure w
ater and 8 mol/l urea solution. These environmental conditions promote
the native and unfolded state of the protein, respectively. The resul
ts are discussed with regard to (i) the low and (ii) the high frequenc
y part of the spectra. The contribution to (i) which is attributable t
o the tumbling motion of RNase is changed by the presence of urea, ind
icating that the RNase moieties are increased in polarity, but only in
significantly in size. From (ii) it is concluded that addition of urea
leads to a change in the overall water structure and dynamics which i
s accompanied by an increased fraction of non-associated solvent molec
ules. These are likely to be instrumental in the denaturation process.