Comparison of Backbone Dynamics of Oxidized and Reduced Putidaredoxin by 15N NMR Relaxation Measurements
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- 作者：Ne
//pubs.acs.org/images/entities/scedil.gif" border="0">e Sari ; Marcia J. Holden ; Martin P. Mayhew ; Vincent L. Vilker ; and Bruce Coxon
- 刊名：Biochemistry
- 出版年：1999
- 出版时间：August 3, 1999
- 年：1999
- 卷：38
- 期：31
- 页码：9862 - 9871
- 全文大小：180K
- 年卷期：v.38,no.31(August 3, 1999)
- ISSN：1520-4995
文摘
The backbone dynamics of uniformly 15N-labeled reduced and oxidized putidaredoxin (Pdx)have been studied by 2D 15N NMR relaxation measurements. 15N T1 and T2 values and 1H-15N NOEshave been measured for the diamagnetic region of the protein. These data were analyzed by using amodel-free dynamics formalism to determine the generalized order parameters (S2), the effective correlationtime for internal motions (
e), and the 15N exchange broadening contributions (Rex) for each residue, aswell as the overall correlation time (m). Order parameters for the reduced Pdx are generally higher thanfor the oxidized Pdx, and there is increased mobility on the microsecond to millisecond time scale for theoxidized Pdx, in comparison with the reduced Pdx. These results clearly indicate that the oxidized proteinexhibits higher mobility than the reduced one, which is in agreement with the recently published redox-dependent dynamics studied by amide proton exchange. In addition, we observed very high T1/T2 ratiosfor residues 33 and 34, giving rise to a large Rex contribution. Residue 34 is believed to be involved inthe binding of Pdx to cytochrome P450cam (CYP101). The differences in the backbone dynamics arediscussed in relation to the oxidation states of Pdx, and their impact on electron transfer. The entropychange occurring on oxidation of reduced Pdx has been calculated from the order parameters of the twoforms.
e), and the 15N exchange broadening contributions (Rex) for each residue, aswell as the overall correlation time (m). Order parameters for the reduced Pdx are generally higher thanfor the oxidized Pdx, and there is increased mobility on the microsecond to millisecond time scale for theoxidized Pdx, in comparison with the reduced Pdx. These results clearly indicate that the oxidized proteinexhibits higher mobility than the reduced one, which is in agreement with the recently published redox-dependent dynamics studied by amide proton exchange. In addition, we observed very high T1/T2 ratiosfor residues 33 and 34, giving rise to a large Rex contribution. Residue 34 is believed to be involved inthe binding of Pdx to cytochrome P450cam (CYP101). The differences in the backbone dynamics arediscussed in relation to the oxidation states of Pdx, and their impact on electron transfer. The entropychange occurring on oxidation of reduced Pdx has been calculated from the order parameters of the twoforms.