Backbone dynamics of the natively unfolded pro-peptide of subtilisin by heteronuclear NMR relaxation studies

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• 作者：Alexei V. Buevich ; Ujwal P. Shinde ; Masayori Inouye and Jean Baum
• 关键词：backbone protein dynamics ; Cole– ; Cole model free analysis ; model free analysis ; 15N relaxation ; natively unfolded proteins ; spectral density mapping
• 刊名：Journal of Biomolecular NMR
• 出版年：2001
• 出版时间：2001
• 年：2001
• 卷：20
• 期：3
• 页码：233-249
• 全文大小：399 KB

文摘

The dynamics of the natively unfolded form of the pro-peptide of subtilisin (PPS) have been characterized at two different pHs (6.0 and 3.0) by 15N relaxation experiments. 15N relaxation data is obtained at multiple field strengths and a detailed comparison of spectral density mapping, the model free approach and the recently proposed Cole–Cole model free (CC-MF) analysis is presented. The CC-MF analysis provides a better fit to the observed magnetic field dependence of 15N relaxation data of unfolded PPS than conventional model free approaches and shows that fluctuations in R₂ may be accounted for by a distribution of correlation times on the nanosecond timescale. A new parameter εderives from the analysis and represents the width of the distribution function and the heterogeneity of the dynamics on the nanosecond timescale at a particular site. Particularly interesting is the observation that ε is sensitive to pH changes and that PPS samples a wider distribution of nanosecond time scale motions at less acidic pHs than at more acidic pHs. These results suggest that PPS experiences a higher degree of correlated motion at pH 6.0 and that electrostatic interactions may be important for inducing correlated motions on the nanosecond timescale in unfolded PPS.