pH-dependent helix folding dynamics of poly-glutamic acid
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- 作者：Edward A. Gooding ; Sapna Sharma ; Sarah A. Petty ; Elizabeth A. Fouts ; Colin J. Palmer ; Brian E. Nolan ; Martin Volk
- 关键词：Protein folding ; Helix&ndash ; coil transition ; Poly-glutamic acid ; Temperature jump ; Time-resolved IR spectroscopy
- 刊名：Chemical Physics
- 出版年：2013
- 出版时间：30 August, 2013
- 年：2013
- 卷：422
- 期：Complete
- 页码：115-123
- 全文大小：479 K
文摘
Poly-L-glutamic acid (PGA) is an ideal model system for investigating the transition between ¦Á-helical and random coil peptide conformations, since its secondary structure is highly sensitive not only to temperature, but also to pH. Laser pulse-induced temperature jumps were used to observe pH-dependent PGA helix-coil relaxation dynamics on the microsecond time scale. The relaxation was found to be non-exponential, particularly if only short helical segments are present before the temperature jump, indicating the multi-step nature of the process which involves helix nucleation and propagation. Helix-coil relaxation is slowest near the mid-point of the pH-induced helix-coil transition, in agreement with theoretical predictions.