Zagorski M G, Norman D G, Barrow C J, Iwashita T, Tachibana K, Patel D J
Department of Biochemistry and Molecular Biophysics, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
Biochemistry. 1991 Aug 13;30(32):8009-17. doi: 10.1021/bi00246a019.
Pardaxin is a mucosal secretion of the Pacific sole Pardachirus pavoninus that exhibits unusual shark repellent and surfactant properties [Thompson, S. A., Tachibana, K., Nakanishi, K., & Kubota, I. (1986) Science 233, 341-343]. This 33 amino acid polypeptide folds into ordered structures in trifluoroethanol-water solution and in micelles but adopts a random-coiled structure in water solution. The complete proton NMR spectrum of pardaxin P-2 has been assigned in CF3CD2OD/H2O (1:1) solution, and the three-dimensional structure has been elucidated with distance restrained molecular dynamics calculations. It is demonstrated that peptide segments within the 7-11 and 14-26 residue stretches are helical while residues at the C- and N-terminus exist predominantly in extended conformations in solution. The dipeptide 12-13 segment connecting the two helices exists as a bend or a hinge allowing the two helices to be oriented in a L-shaped configuration. These studies establish that pardaxin P-2 adopts a novel amphiphilic helix (7-11)-bend (12-13)-helix (14-26) motif with Pro-13 forming the focal point of the turn or bend between the two helices.
豹鳎毒素是太平洋鳎鱼（Pardachirus pavoninus）的一种黏膜分泌物，具有独特的驱鲨和表面活性剂特性[汤普森，S. A.，立花，K.，中岸，K.，& 久保田，I.（1986年）《科学》233卷，341 - 343页]。这种由33个氨基酸组成的多肽在三氟乙醇 - 水溶液和胶束中折叠成有序结构，但在水溶液中呈无规卷曲结构。豹鳎毒素P - 2的完整质子核磁共振谱已在CF3CD2OD/H2O（1:1）溶液中归属，其三维结构已通过距离约束分子动力学计算阐明。结果表明，7 - 11和14 - 26残基段内的肽段呈螺旋状，而C端和N端的残基在溶液中主要以伸展构象存在。连接两个螺旋的二肽12 - 13段以弯曲或铰链形式存在，使两个螺旋呈L形排列。这些研究表明，豹鳎毒素P - 2采用了一种新型的两亲性螺旋（7 - 11）-弯曲（12 - 13）-螺旋（14 - 26）基序，其中Pro - 13形成了两个螺旋之间转角或弯曲的焦点。
