Table 1. Properties of some of the more relevant arginine-metabolising enzymes in this study.

Enzyme	EC number	Substrate(s)	Cofactors/ions/etc	Products	Km (mM)
Arginase	3.5.3.1	Arginine	Mn2+	Ornithine and urea	10.5
Arginine decarboxylase	4.1.1.19	Arginine	Pyridoxal phosphate	Agmatine and CO2	∼1
Arginine deiminase	3.5.3.6	Arginine	Mg2−	Citrulline and NH3	∼0.1–0.2
Nitric oxide synthase	1.14.13.39	Arginine (made from citrulline) and O2	NADPH→NADP+	NO and citrulline	0.03