Zinc(II) complexes of tripodal peptides mimicking the zinc(II)-coordination structure of carbonic anhydrase.

Two new tripodal peptide ligands with histidine side chains have been synthesized and were shown to form stable zinc(II) complexes. Their NMR and mass spectra indicate a structure that is analogous to the active center of carbonic anhydrase. Both the ligands and the zinc complexes were titrated potentiometrically in order to obtain the pKa values for the coordinated water of the zinc complexes; due to the low solubility of the complexes only estimates could be obtained.