2 H(+) + H2O + urea = CO2 + 2 NH4(+) Binds 2 nickel ions per subunit. Inhibited by HgCl2 and acetohydroxyamic acid slightly by EDTA, but not by boric acid or L-methionine-DL-sulfoximine. Optimum temperature is 55 degrees Celsius. Nitrogen metabolism; urea degradation; CO(2) and NH(3) from urea (urease route): step 1/1. Heterotrimer of UreA (gamma), UreB (beta) and UreC (alpha) subunits. Two heterotrimers associate to form the active enzyme. In most bacteria it is thought that three heterotrimers form the active enzyme. Carboxylation allows a single lysine to coordinate two nickel ions. Belongs to the metallo-dependent hydrolases superfamily. Urease alpha subunit family.