Synthesis, 1 H, 13 C, 15 N, and 113 Cd NMR, ESI-TOF MS, Semiempirical MO (PM3), ab initio/HF and Cation/Anion Binding Studies of N-deoxycholyl-L-tryptophan

摘要: The synthesis, structural characterization, and cation/anion binding properties ofa new bile acid-amino acid conjugate, N-deoxycholyl-l-tryptophan, aredescribed. structures of the ligand its cadmium adduct at different pHconditions various perchlorate concentrations were determined bymodern multinuclear magnetic resonance spectroscopic as well ESI-TOF MStechniques. Also semiempirical PM3 ab initio/HF molecular modellingstudies performed. Based on 1H,1H NOESY measurementsN-deoxycholyl-l-tryptophan in alkaline conditions was found to appearin a bent conformation which clearly from conformations neutraland acidic solutions. According modelling minimum energy structurethe tryptophan backbone folded close deoxycholic skeletonand structure stabilized by an intramolecular hydrogen bond. multinuclearmagnetic experiments indicated that Cd2+-cation bound with theligand neutral while protons block thebinding site. MS revealed competition between sodium cadmiumions, having stronger affinity for sodium. Cadmium occurred onlywhen excess used. Further, spectra showed variouschlorine oxyanions originated anion formed together cationsdifferent adducts ligand.