Studies of β-turn opening with model peptides containing non-coded α-amino isobutyric acid
作者:Anita Dutt、Arpita Dutta、Raju Mondal、Elinor C. Spencer、Judith A.K. Howard、Animesh Pramanik
DOI:10.1016/j.tet.2007.07.075
日期:2007.10
Single crystal X-ray diffraction studies show that among the three terminally protected model tripeptides I–III, Boc-Ile-Aib-Xx–OMe (Xx in peptide I: Val; II: Leu; III: Phe) with a centrally placed non-coded amino acid Aib (Aib: α-amino isobutyric acid), peptide I displays a conformational preference for β-turn, peptide II forms a hydrated β-turn representing the solvent mediated intermediate for the
单晶X射线衍射研究表明,在三个末端受保护的模型三肽I – III中,Boc-Ile-Aib-Xx-OMe(肽I中的Xx :Val;II:Leu;III:Phe)具有非中心位置编码的氨基酸Aib(Aib:α-氨基异丁酸),肽段I对β-turn显示构象偏好,肽段II形成水合的β-turn,代表溶剂介导的中间体,用于β-turn和β-strand之间的相互转化和肽III采用完全展开的β链状结构。通过改变第三残基的空间体积Xx(3),已分离出与β-转角和β-链之间的结构互变有关的各种构象。溶液相中的肽构象已通过溶剂依赖性NMR滴定和CD光谱法进行了探测。扫描电子显微镜(SEM)的形态学研究表明,在三种肽中,只有肽III可以形成固态的丝状原纤维。