3.5.1.54 urea-1-carboxylate + H2O = 2 CO2 + 2 NH3 - - 3.5.1.54 urea-1-carboxylate + H2O = 2 CO2 + 2 NH3 the catalytic triad consists of residues Ser177, Ser153, and Lys79 -, 668661 3.5.1.54 urea-1-carboxylate + H2O = 2 CO2 + 2 NH3 two-step reaction catalytic mechanism of the C-domain, overview. The C-domain probably catalyzes a distinct form of decarboxylation reaction 734220