Sirish Mallena, Chertkov Vyacheslav A, Schneider Hans-Jörg
FR 11.2 Organische Chemie, Universität des Saarlandes, 66041 Saarbrücken, Germany.
Chemistry. 2002 Mar 1;8(5):1181-8. doi: 10.1002/1521-3765(20020301)8:5<1181::aid-chem1181>3.0.co;2-u.
The synthesis and purification of a water-soluble host compound that contains three pyridinium units and one spacer-connected benzocrown ether unit in the meso-positions of porphyrin and of its Zn(II) or Cu(II) complexes is described. Metalation leads to small (compared to the apo-derivative) changes of selectivities with different peptides, with complexation constants in water of above 10(5)M(-1). One complex containing the tripeptide Gly-Gly-Phe is analyzed in detail by COSY, HSQC, HMBC, and NOESY NMR experiments. Temperature-dependent spectra show activation energies for a intramolecular hydrogen exchange of amide protons with valence isomerization of the porphyrin ring, in accordance with the literature. Sharp signals for the spin system are only found at elevated temperature. Vicinal coupling constants within the crown ether moiety indicate stronger puckering than that reported for benzocrowns. All NMR signals of the complexed peptide are shielded, in particular those of the terminal phenylalanine unit, in line with its stacking on the porphyrin surface. A corresponding structural model, obtained by CHARMm simulation, is also in line with the observed intermolecular NOE cross peaks.
本文描述了一种水溶性主体化合物的合成与纯化，该化合物在卟啉的中位含有三个吡啶鎓单元和一个通过间隔基连接的苯并冠醚单元，以及其锌（II）或铜（II）配合物。金属化导致与不同肽的选择性发生微小（与脱辅基衍生物相比）变化，在水中的络合常数高于10⁵M⁻¹。通过COSY、HSQC、HMBC和NOESY NMR实验详细分析了一种含有三肽甘氨酸-甘氨酸-苯丙氨酸的配合物。与文献一致，温度相关光谱显示了酰胺质子分子内氢交换与卟啉环价异构化的活化能。仅在升高的温度下发现自旋系统的尖锐信号。冠醚部分内的邻位耦合常数表明其褶皱比报道的苯并冠醚更强。络合肽的所有NMR信号都被屏蔽，特别是末端苯丙氨酸单元的信号，这与其在卟啉表面的堆积情况一致。通过CHARMm模拟获得的相应结构模型也与观察到的分子间NOE交叉峰一致。
