Supramolecular Catalysis of H/D Exchange in Malonate Ions by Macrocyclic Polyamines: A Model Enzyme with Enolase Activity

In three ways at once the macrocyclic polyamine [24]aneN6O2 promotes the H/D exchange at the α position in malonate ions: The quadruply protonated species in neutral pH range forms a quite stable dicationic complex (1) with the malonate dianion, which facilitates the approach of a base and assists the enolization through the acidic NH+ centers. The acceleration factor for the fourfold protonated polyamine [24]aneN6O2 is kcat/kuncat ≈ 1.4 × 103.