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[摘要]：A chiral C3-sym. enterobactin analog (I) was synthesized by attachment of three 2,3-dihydroxybenzoyl units to a chiral oxazole-contg. macrocyclic peptide scaffold. Complex formation kinetics and stoichiometry with various metal ions were investigated by spectrophotometric methods. In the cases of AlIII, InIII and FeIII complexes, UV absorption and CD kinetics showed nonlinearity, which results from slow conformational changes of the octahedral complexes. Virtual binding consts. were detd. from UV absorption data and showed selective binding of GaIII in preference to FeIII, by two orders of magnitude. CD spectroscopy revealed highly diastereoselective binding of AlIII, GaIII, InIII, FeIII and GeIV ions at room temp., corresponding to the helical chirality opposite to that of the analogous enterobactin complexes. Ab initio calcns. confirmed the energetic stabilization of the L isomers relative to the D isomers. |
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