2.2 SQUARE inside PROTEIN p0 inside PROTEIN p1 inside SIMPLE_MOLECULE CO2 inside SIMPLE_MOLECULE Urea inside SIMPLE_MOLECULE L_minus_Citrulline inside SIMPLE_MOLECULE Carbamoyl_space_phosphate inside SIMPLE_MOLECULE L_minus_Ornithine STATE_TRANSITION Urea CO2 c1 c0 STATE_TRANSITION Carbamoyl_space_phosphate L_minus_Citrulline c3 c4 c2