Urease

First coordination sphere of the Ni²⁺ atoms

The Ni²⁺ atoms are connected by a water molecule (O1) and both oxygen atoms (OX1, OX2) of a lysine residue (LYS 217).

In addition, each Ni atom is coordinated by two histidine residues (through one N atom each) and a water molecule.

The sixth coordination site of the one Ni atom is occupied by the oxygen atom of an aspartic acid residue (ASP 360).

In the first coordination sphere, only the nickel atoms and the non-bridging water molecules (O2, O3) directly participate in the mechanism of the catalytic urea degradation.

  Click here for a possible mechanism of catalytic urea degradation