Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are a family of molecules called gasotransmitters. Research into the biological role of gasotransmitters has grown rapidly, and it is now recognized that they are not classical signaling molecules but are regulators of cellular function through complex chemical interactions with each other (including metabolites) and target proteins. Each gasotransmitter has a dependence on O2, as it is required for NO and CO synthesis and H2S metabolism, and the three gases can form coordination chemistries with the heme of target proteins, which is critical for regulating such proteins. Gasotransmitters are involved in control of a vast array of physiological functions, including regulation of the cardiovascular, nervous, gastrointestinal, excretory, and immune systems, in addition to many cellular functions, including apoptosis, proliferation, inflammation, cellular metabolism, oxygen sensing, and gene transcription.
