3.5.1.5	urea + H2O = CO2 + 2 NH3	active site contains three ionazable groups with pKa-values of 5.3, 6.6 and 9.0 that participate both in catalysis and substrate binding	670611	
3.5.1.5	urea + H2O = CO2 + 2 NH3	mechanism	209179