Fezoui Y, Weaver D L, Osterhout J J
Rowland Institute for Science, Cambridge, MA 02142.
Proc Natl Acad Sci U S A. 1994 Apr 26;91(9):3675-9. doi: 10.1073/pnas.91.9.3675.
The de novo design and structural characterization of an alpha-helical hairpin peptide (alpha-helix/turn/alpha-helix, alpha t alpha) are reported. The peptide is intended to provide a model system for the study of the interactions of secondary structural elements during protein folding. Both the diffusion-collision and framework models of protein folding envision that the earliest intermediates in protein folding are transient secondary structures or microdomains which interact and become mutually stabilizing. Design principles for the alpha t alpha peptide were drawn from the large body of work on the structure of peptides in solution. Computer modeling was not used in the design process. Study of alpha t alpha by circular dichroism and two-dimensional nuclear magnetic resonance indicates that the designed peptide is monomeric, helical, and stable in aqueous solution at room temperature. Analysis of two-dimensional nuclear magnetic resonance experiments indicates that the two helices and the turn form in the intended positions and that the helices associate in the designed orientation. Development of alpha t alpha represents an advance in protein design in that both the secondary structural elements and designed tertiary interactions have been realized and can be detected in solution by nuclear magnetic resonance. The resulting model system resembles a protein folding intermediate and will allow the study of interacting helices in a context that approximates an early stage in protein folding.
本文报道了一种α-螺旋发夹肽（α-螺旋/转角/α-螺旋，αtα）的从头设计及其结构表征。该肽旨在为研究蛋白质折叠过程中二级结构元件之间的相互作用提供一个模型系统。蛋白质折叠的扩散碰撞模型和框架模型都设想，蛋白质折叠最早的中间体是相互作用并相互稳定的瞬时二级结构或微结构域。αtα肽的设计原则源于大量关于溶液中肽结构的研究工作。设计过程中未使用计算机建模。通过圆二色性和二维核磁共振对αtα的研究表明，所设计的肽在室温下的水溶液中是单体、螺旋状且稳定的。二维核磁共振实验分析表明，两条螺旋和转角在预期位置形成，且螺旋以设计的方向缔合。αtα的开发代表了蛋白质设计的一项进展，因为二级结构元件和设计的三级相互作用都已实现，并且可以通过核磁共振在溶液中检测到。由此产生的模型系统类似于蛋白质折叠中间体，将有助于在接近蛋白质折叠早期阶段的背景下研究相互作用的螺旋。
