Toniolo C, Crisma M, Formaggio F, Peggion C
Department of Organic Chemistry, University of Padova, Institute of Biomolecular Chemistry, CNR, 35131 Padova, Italy.
Biopolymers. 2001;60(6):396-419. doi: 10.1002/1097-0282(2001)60:6<396::AID-BIP10184>3.0.CO;2-7.
The preferred conformations of peptides heavily based on the currently extensively exploited achiral and chiral alpha-amino acids with a quaternary alpha-carbon atom, as determined by conformational energy computations, crystal-state (x-ray diffraction) analyses, and solution ((1)H-NMR and spectroscopic) investigations, are reviewed. It is concluded that 3(10)/alpha-helical structures and the fully extended (C(5)) conformation are preferentially adopted by peptide sequences characterized by this family of amino acids, depending upon overall bulkiness and nature (e.g., whether acyclic or C(alpha) (i) <--> C(alpha) (i) cyclized) of their side chains. The intriguing relationship between alpha-carbon chirality and bend/helix handedness is also illustrated. gamma-Bends and semiextended conformations are rarely observed. Formation of beta-sheet structures is prevented.
通过构象能量计算、晶体状态（X射线衍射）分析和溶液（（1）H-NMR和光谱）研究确定，基于目前广泛使用的具有季α-碳原子的非手性和手性α-氨基酸的肽的优选构象进行了综述。得出的结论是，由该氨基酸家族表征的肽序列优先采用3(10)/α-螺旋结构和完全伸展（C(5)）构象，这取决于它们侧链的整体体积和性质（例如，是否为无环或Cα(i) <--> Cα(i) 环化）。还说明了α-碳手性与弯曲/螺旋手性之间的有趣关系。很少观察到γ-弯曲和半伸展构象。β-折叠结构的形成受到阻碍。
