Zitzewitz J A, Ibarra-Molero B, Fishel D R, Terry K L, Matthews C R
Department of Chemistry, Life Sciences Consortium, and Center for Biomolecular Structure and Function, The Pennsylvania State University, PA 16802, USA.
J Mol Biol. 2000 Mar 3;296(4):1105-16. doi: 10.1006/jmbi.2000.3507.
The structure of the transition state for the rate-limiting step in the folding and association of the homodimeric coiled-coil peptide GCN4-p1, was probed by mutational analysis. A series of quadruple amino acid replacements that spanned the helix propensity scale were made at the four external f positions in the heptad repeat. Equilibrium and kinetic circular dichroism studies demonstrate that both the stability and the unfolding and refolding rate constants vary with helix propensity but also reflect interactions of the altered side-chains with their local environments. Pairwise replacements and fragment studies show that the two C-terminal heptads are the likely source of the nucleating helices. Helix-helix recognition between preformed elements of secondary structure plays an important role in this fundamental folding reaction.
通过突变分析探究了同二聚体卷曲螺旋肽GCN4-p1折叠和缔合限速步骤的过渡态结构。在七肽重复序列的四个外部f位置进行了一系列跨越螺旋倾向范围的四重氨基酸替换。平衡和动力学圆二色性研究表明，稳定性以及解折叠和重折叠速率常数均随螺旋倾向而变化，但也反映了改变后的侧链与其局部环境的相互作用。成对替换和片段研究表明，两个C端七肽可能是成核螺旋的来源。二级结构的预形成元件之间的螺旋-螺旋识别在这一基本折叠反应中起重要作用。
