Aspartate/asparagine-β-hydroxylase (AspH) is a human 2-oxoglutarate (2OG) and FeII oxygenase that catalyses C3 hydroxylations of aspartate/asparagine residues of epidermal growth factor-like domains (EGFDs). Unusually, AspH employs two histidine residues to chelate FeII rather than the typical triad of two histidine and one glutamate/aspartate residue. We report kinetic, inhibition, and crystallographic studies concerning human AspH variants in which either of its FeII binding histidine residues are substituted for alanine. Both the H725A and, in particular, the H679A AspH variants retain substantial catalytic activity. Crystal structures clearly reveal metal-ligation by only a single protein histidine ligand. The results have implications for the functional assignment of 2OG oxygenases and for the design of non-protein biomimetic catalysts.
A human 2‐oxoglutarate and FeII dependent oxygenase was engineered to possess only one protein FeII binding ligand. The resultant variants retained significant levels of catalytic activity. Biomimetic catalysts containing only one metal binding site are therefore of interest.
Keywords: 2-oxoglutarate dependent oxygenase; aspartate/asparagine-β-hydroxylase; biomimetic catalysis; facial triad; metallo-enzymes.
© 2021 The Authors. Angewandte Chemie published by Wiley-VCH GmbH.