Fig. 1
From: Bench to bedside review: therapeutic modulation of nitric oxide in sepsis—an update
Nitric oxide synthase (NOS) cofactors and activity. NOS enzymes function as homodimers within subunits structurally supported by a Zinc ion (Zn2+). Following sequestration of iron, the binding site for arginine is expressed. Electron transfer also depends on flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) availability and the binding of calmodulin (CaM) which is calcium dependent for eNOS and nNOS and independent for iNOS. NADPH, oxygen and tetrahydrobiopterin (BH4) are essential cofactors for the synthesis of nitric oxide