Dielectric relaxation of aqueous solutions of ribonuclease A in the absence and presence of urea

被引:18
作者
Abou-Aiad, T [1 ]
Becker, U [1 ]
Biedenkap, R [1 ]
Brengelmann, R [1 ]
Elsebrock, R [1 ]
Hinz, HJ [1 ]
Stockhausen, M [1 ]
机构
[1] Univ Munster, Inst Chem Phys, D-48149 Munster, Germany
来源
BERICHTE DER BUNSEN-GESELLSCHAFT-PHYSICAL CHEMISTRY CHEMICAL PHYSICS | 1997年 / 101卷 / 12期
关键词
biophysical chemistry; dielectrics; solutions;
D O I
10.1002/bbpc.19971011219
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The dielectric spectra of aqueous solutions of ribonuclease A (RNase) have been measured in the frequency domain over the whole absorption region between 2 MHz and 72 GHz at 20 degrees C in two solvents, pure water and 8 mol/l urea solution. These environmental conditions promote the native and unfolded state of the protein, respectively. The results are discussed with regard to (i) the low and (ii) the high frequency part of the spectra. The contribution to (i) which is attributable to the tumbling motion of RNase is changed by the presence of urea, indicating that the RNase moieties are increased in polarity, but only insignificantly in size. From (ii) it is concluded that addition of urea leads to a change in the overall water structure and dynamics which is accompanied by an increased fraction of non-associated solvent molecules. These are likely to be instrumental in the denaturation process.
引用
收藏
页码:1921 / 1927
页数:7
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