Thomas R M, Zampieri A, Jumel K, Harding S E
Institut für Polymere, ETH-Zentrum, Zurich, Switzerland.
Eur Biophys J. 1997;25(5-6):405-10. doi: 10.1007/s002490050053.
Alpha-helical coiled coils are proving to be almost ideal systems for the modelling of peptide and protein self-association processes. Stable oligomeric systems, in which the stoichiometry is well defined, can be produced by the careful selection of the appropriate amino acid sequence, although the principles behind this are still not fully understood. Here we report on a 35 residue peptide, FZ, synthesized by the solid phase method, which was originally designed to form a dimer, but which, in fact, associates to the trimeric state. A detailed characterization of the associative properties of the peptide has been performed by circular dichroism spectroscopy and, in particular, by sedimentation equilibrium in the analytical ultracentrifuge. The presence of the trimeric state, which is stable even at low peptide concentrations, has been confirmed by various independent methods of analysis for molar mass. The effects of both temperature and of guanidinium chloride on the peptide have been investigated and both found to be peptide-concentration dependent. The unfolding induced by the denaturant cannot be adequately described by a simple, two state monomer-trimer equilibrium.
事实证明，α-螺旋卷曲螺旋几乎是模拟肽和蛋白质自组装过程的理想系统。通过精心选择合适的氨基酸序列，可以构建化学计量明确的稳定寡聚体系统，尽管其背后的原理仍未完全明晰。在此，我们报告一种通过固相法合成的35个残基的肽FZ，它最初设计为形成二聚体，但实际上会缔合形成三聚体状态。通过圆二色光谱，特别是通过分析超速离心机中的沉降平衡，对该肽的缔合特性进行了详细表征。通过各种独立的摩尔质量分析方法，证实了即使在低肽浓度下三聚体状态也稳定存在。研究了温度和氯化胍对该肽的影响，发现二者均与肽浓度有关。变性剂诱导的去折叠不能用简单的二态单体-三聚体平衡来充分描述。
