Steric Effects on the Chelation of Mn and Zn by Hexadentate Polyimidazole Ligands: Modeling Metal Binding by Calprotectin Site 2.

Recently, there has been increasing interest in the design of ligands that bind Mn with high affinity and selectivity, but this remains a difficult challenge. It has been proposed that the cavity size of the binding pocket is a critical factor in most synthetic and biological examples of selective Mn binding. Here, we use a bioinspired approach adapted from the hexahistidine binding site of the manganese-sequestering protein calprotectin to systematically study the effect of cavity size on Mn and Zn binding.