Reaction catalyzed by 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase (4.1.1.97)

		=			+
	5-hydroxy-2-oxo-4-ureido-2,5-dihydro-1H-imidazole-5-carboxylate	=		(S)-allantoin	+		CO2