A novel citrulline-forming enzyme implicated in the formation of nitric oxide by vascular endothelial cells.

An enzyme in homogenates of porcine vascular endothelial cells forms L-citrulline from L-arginine. This enzyme is soluble and NADPH-dependent. In addition, the enzyme is inhibited by NG-monomethyl-L-arginine, suggesting that it is involved in the formation of nitric oxide by vascular endothelial cells.