Produces nitric oxide (NO) which is a messenger molecule involved in hormonal signaling and defense responses in plant. H(+) + 2 L-arginine + 3 NADPH + 4 O2 = 4 H2O + 2 L-citrulline + 3 NADP(+) + 2 nitric oxide Belongs to the TRAFAC class YlqF/YawG GTPase family. NOA1 subfamily.