l-Arginine analogs as alternate substrates for nitric oxide synthase

The l-arginine analogs, Nδ-methyl-l-arginine (δMA) and l-canavanine, were used to probe the role of the Nδ nitrogen of l-arginine in the reaction catalyzed by nitric oxide synthase (NOS). δMA was synthesized and found to be a partial alternate substrate and a weak, reversible inhibitor of NOS with a Ki equal to 1.4 mM. δMA undergoes hydroxylation; however, it is not converted further, hence it functions as a partial substrate. l-Canavanine was converted to an l-homoserine presumably via initial hydroxylation and decomposition. The mechanism of this reaction and products of this reaction were not probed further.