Sequence-specific recognition and cooperative dimerization of N-terminal aromatic peptides in aqueous solution by a synthetic host
Sequence-specific recognition and cooperative dimerization of N-terminal aromatic peptides in aqueous solution by a synthetic host
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DOI：
10.1021/ja064323s
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发表时间：
2006-09-27
影响因子：
15
通讯作者：
Urbach, Adam R.
中科院分区：
文献类型：
--
作者：
Heitmann, Lisa M.;Taylor, Alexander B.;Urbach, Adam R.
本文描述了合成主体化合物葫芦[8]uril (Q8) 对水溶液中N 端芳香肽的选择性识别和非共价二聚化。已知 Q8 可同时结合两个芳香族客体，并且在甲基紫精存在的情况下，可识别内部和 C 端序列异构体上的 N 端色氨酸。在这里，通过等温滴定量热法 (ITC)、H-1 NMR 光谱和 X 射线晶体学研究了在没有甲基紫精的情况下 Q8 与芳香肽的结合。研究的肽序列为 X-Gly-Gly、Gly-X-Gly 和 Gly-Gly-X（X = Trp、Phe、Tyr 和 His）。 Q8 以高亲和力选择性结合 Trp-Gly-Gly (1) 和 Phe-Gly-Gly (4) 并二聚化（三元 K = 10(9)-10(11) M-2）；其他 10 种肽的结合常数太小，无法通过 ITC 进行测量。两种肽均逐步结合，肽4呈正协同结合。 Q8, 1 和 Q8, 42 的晶体结构揭示了选择性识别的基础，即同时将疏水芳族侧链纳入 Q8 的空腔中，并通过 Q8 的羰基螯合近端 N 末端铵基团。据我们所知，这里报道的肽序列选择性和正协同二聚化对于水溶液中的合成宿主来说是前所未有的。合成宿主（例如 Q8）的特异性肽识别和二聚化对于二聚体介导的生化过程的研究以及肽和蛋白质的分离应该很重要。
This article describes the selective recognition and noncovalent dimerization of N-terminal aromatic peptides in aqueous solution by the synthetic host compound, cucurbit[8]uril (Q8). Q8 is known to bind two aromatic guests simultaneously and, in the presence of methyl viologen, to recognize N- terminal tryptophan over internal and C-terminal sequence isomers. Here, the binding of Q8 to aromatic peptides in the absence of methyl viologen was studied by isothermal titration calorimetry (ITC), H-1 NMR spectroscopy, and X-ray crystallography. The peptides studied were of sequence X-Gly-Gly, Gly-X-Gly, and Gly-Gly-X (X = Trp, Phe, Tyr, and His). Q8 selectively binds and dimerizes Trp-Gly-Gly (1) and Phe-Gly-Gly (4) with high affinity (ternary K = 10(9)-10(11) M-2); binding constants for the other 10 peptides were too small to be measured by ITC. Both peptides bound in a stepwise manner, and peptide 4 bound with positive cooperativity. Crystal structures of Q8, 1 and Q8, 42 reveal the basis for selective recognition as simultaneous inclusion of the hydrophobic aromatic side chain into the cavity of Q8 and chelation of the proximal N-terminal ammonium group by carbonyl groups of Q8. The peptide sequence selectivity and positively cooperative dimerization reported here are, to the best of our knowledge, unprecedented for synthetic hosts in aqueous solution. Specific peptide recognition and dimerization by synthetic hosts such as Q8 should be important in the study of dimer-mediated biochemical processes and for the separation of peptides and proteins.