Urease <p>Urease (urea amidohydrolase, <db_xref db="EC" dbkey="3.5.1.5"/>) catalyses the hydrolysis of urea to form ammonia and carbamate. The subunit composition of urease from different sources varies [<cite idref="PUB00010725"/>], but each holoenzyme consists of four structural domains [<cite idref="PUB00005206"/>]: three structural domains and a nickel-binding catalytic domain common to amidohydrolases [<cite idref="PUB00004994"/>]. Urease is unique among nickel metalloenzymes in that it catalyses a hydrolysis rather than a redox reaction. In <taxon tax_id="28451">Klebsiella aerogenes</taxon>, the domains are found in an alpha subunit (with the C-terminal two-thirds representing the catalytic domain and the N-terminal one-third representing one of the structural domains; <db_xref db="INTERPRO" dbkey="IPR008295"/>), a beta subunit (<db_xref db="INTERPRO" dbkey="IPR008222"/>), and a gamma subunit (<db_xref db="INTERPRO" dbkey="IPR012010"/>). In <taxon tax_id="210">Helicobacter pylori</taxon>, the gamma and beta domains are fused and called the alpha subunit (<db_xref db="INTERPRO" dbkey="IPR008223"/>). The catalytic subunit (called beta or B) has the same organisation as the K. aerogenes alpha subunit. Jack bean (<taxon tax_id="3823">Canavalia ensiformis</taxon>) urease has a fused gamma-beta-alpha organisation.</p><p>This group represents the gamma-beta-alpha type.</p>