Crystal conformation of the cyclic decapeptide phakellistatin 8: Comparison with antamanide
Crystal conformation of the cyclic decapeptide phakellistatin 8: Comparison with antamanide
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DOI：
10.1021/ja9626648
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发表时间：
1997-07-30
影响因子：
15
通讯作者：
Srirangam, JK
中科院分区：
文献类型：
--
作者：
Herald, DL;Cascarano, GL;Srirangam, JK
用X射线衍射法测定了环十肽phakellistatin 8的固态构象，即cyclo[Pro（1）-Pro（2）-Ile（3）-Phe（4）-瓦尔（5）-Leu（6）-Pro（7）-Pro（8）-Tyr（9）-Ile（10）]。[晶体数据：正交晶系; P2（1）2（1）2; a 20.294（2），B = 24.141（6），c = 13.903（3）埃。10061个反射的最小二乘细化（I > 2 sigma（I））导致残差R-1 = 0.0651（Sheldrick wR（2）= 0.1749）。]环状十肽包括（1）5->1个跨环α转角型PI键，包括Pro（1）、Pro（2）和Ile（3）残基并涉及Phe（4）酰胺氢和Ile（10）羰基，（2）分子内3->1个VIa型γ转角型II键，包含Phe（4）残基并涉及瓦尔（5）酰胺氢和Ile（3）羰基，和（3）分子内4->1型VIa β-转角H-键，包括Pro（7）和Pros残基并涉及Tyr（9）酰胺氢和Leu（6）羰基。除了两个氨基酸残基Phe（4）（Phi，Psi = 71度，-41度）和Tyr（9）（Phi，Psi = 75度，31度）之外，所有骨架二面角都落在正常的低能区域内，发现其侧链在肽骨架上折回。phakellistatin 8的四个脯氨酸残基的构象可以分类如下：Pro（1）C-s-C（gamma）exo、Pro（2）C-2-C（beta）exo（C（gamma）endo）、Pro（7）C-s-C（gamma）endo和Pro（8）C-2-C（beta）exo（C（gamma）endo）。phakellistatin 8和十肽antamanide的检查表明，这两种化合物是非常相似的，无论是在整体骨架构象，脯氨酸环构象，并存在几乎相同的α-金枪鱼涉及的Pro-Pro对之一。当从水性溶剂中结晶时，这两种分子都高度水合，并且在固态下都表现出通道形成。
The solid-state conformation of the cyclic decapeptide phakellistatin 8, cyclo[Pro(1)-Pro(2)-Ile(3)-Phe(4)-Val(5)-Leu(6)-Pro(7)-Pro(8)-Tyr(9)-Ile(10)] has been determined by X-ray methods. [Crystal data: orthorhombic; P2(1)2(1)2; a 20.294(2), b = 24.141(6), c = 13.903(3) Angstrom. Least-squares refinement of 10061 reflections (I > 2 sigma(I)) led to residuals R-1 = 0.0651 (Sheldrick wR(2) = 0.1749).] The cyclic decapeptide includes (1) a 5-->1 transannular ct-turn type PI-bond, encompassing the Pro(1), Pro(2), and Ile(3) residues and involving the Phe(4) amide hydrogen and the Ile(10) carbonyl, (2) an intramolecular 3-->1 type VIa gamma-turn type of II-bond, encompassing the Phe(4) residue and involving the Val(5) amide hydrogen and the Ile(3) carbonyl, and (3) an intramolecular 4-->1 type VIa beta-turn H-bond, encompassing the Pro(7) and Pros residues and involving the Tyr(9) amide hydrogen and the Leu(6) carbonyl. All backbone dihedral angles fall within normal, low-energy regions except for two amino acid residues, Phe(4) (Phi, Psi = 71 degrees, -41 degrees) and Tyr(9) (phi, Psi = 75 degrees, 31 degrees), the side chains of which are found to fold back over the peptide backbone. Conformations of the four proline residues for phakellistatin 8 can be classified as follows: Pro(1) C-s-C(gamma)exo, Pro(2) C-2-C(beta)exo(C(gamma)endo), Pro(7) C-s-C(gamma)endo and Pro(8) C-2-C(beta)exo(C(gamma)endo). Examination of phakellistatin 8 and the decapeptide antamanide show the two compounds are quite similar, both in overall backbone conformation, proline ring conformations, and the presence of nearly identical alpha-tunas involving one of the Pro-Pro pairs. Both molecules are highly hydrated when crystallized from aqueous solvents and both exhibit channel formation in the solid state.