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Sequence-specific DNA-binding dominated by dehydration
被引:62
作者:
Lundback, T
Hard, T
机构:
[1] KAROLINSKA INST,NOVUM,CTR STRUCT BIOCH,S-14157 HUDDINGE,SWEDEN
[2] ROYAL INST TECHNOL,NOVUM,CTR STRUCT BIOCH,S-14157 HUDDINGE,SWEDEN
来源:
关键词:
DNA-protein interactions;
thermodynamics;
hydrophobic effect;
isothermal titration calorimetry;
fluorescence spectroscopy;
D O I:
10.1073/pnas.93.10.4754
中图分类号:
O [数理科学和化学];
P [天文学、地球科学];
Q [生物科学];
N [自然科学总论];
学科分类号:
07 ;
0710 ;
09 ;
摘要:
qFluorescence spectroscopy and isothermal titration calorimetry were used to study the thermodynamics of binding of the glucocorticoid receptor DNA-binding domain to four different, but similar, DNA-binding sites. The binding sites are two naturally occurring sites that differ in the composition of one base pair, i.e., A . T to G . C mutation, and two sites containing chemical intermediates of these base pairs. The calorimetrically determined heat capacity change (Delta C-p degrees(obs)) for glucocorticoid receptor DNA-binding domain binding agrees with that calculated for dehydration or solvent-accessible surface areas. A dominating effect of dehydration or solvent reorganization on the thermodynamics is also consistent with an observed linear relationship between observed enthalpy change (Delta H degrees(obs)) and observed entropy change (Delta S degrees(obs)) with a slope close to the experimental temperature. Comparisons with structural data allow us to rationalize individual differences between Delta H degrees(obs) (and Delta S degrees(obs)) for the four complexes. For instance, we find that the removal of a methyl group at the DNA-protein interface is enthalpically favorable but entropically unfavorable, which is consistent with a replacement by an ordered water molecule.
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页码:4754 / 4759
页数:6
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