Nitric oxide is synthesised from:
NO is synthesized from l-arginine by the enzyme nitric oxide synthase (NOS). There are three different types of NOS: endothelial (eNOS), neuronal (nNOS), and inducible (iNOS). eNOS and nNOS are constitutively expressed at low levels and can be activated rapidly by an increase in cytoplasmic Ca2+. iNOS, in contrast, is induced when macrophages and other cells are activated by cytokines (e.g., TNF, IFN-g) or microbial products. Ref: Robbins 8th edition, Chapter 2.
Cysteine
Cystine
Methionine
Arginine