Nitric Oxide Synthase: Difference between revisions
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Each NOS monomer is composed of two domains: an N-terminal oxygenase domain and a C-terminal reductase domain. Each subunit is held together by a zinc ion, which is bound by two cysteines from each oxygenase domain. Calmoduling binds to a linker region between the two domains and is necessary for activity. The reductase domain supplies electrons for the NOS reaction which takes place in the oxygenase domain. The reductase domain contains two redox-active prosthetic groups, flavin adenine dinucleotide (FAD) and Flavin mononucleotide (FMN). Nicotinamide adenine dinucleotide phosphate(NADPH) binds to the domain and passes on an electron to FAD which passes the electron on to FMN. FMN passes the electron on to the heme in the oxygenase domain on the opposite subunit. The oxygenase domain contains 5,6,7,8-tetrahydrobiopterin (H<sub>4</sub>B) and the already mentioned heme. These two are also redox active groups. Besides Heme and H<sub>4</sub>B, the oxygenase domain binds the substrate L-arginine which takes part in the NO synthase reaction (see below). | Each NOS monomer is composed of two domains: an N-terminal oxygenase domain and a C-terminal reductase domain. Each subunit is held together by a zinc ion, which is bound by two cysteines from each oxygenase domain. Calmoduling binds to a linker region between the two domains and is necessary for activity. The reductase domain supplies electrons for the NOS reaction which takes place in the oxygenase domain. The reductase domain contains two redox-active prosthetic groups, flavin adenine dinucleotide (FAD) and Flavin mononucleotide (FMN). Nicotinamide adenine dinucleotide phosphate(NADPH) binds to the domain and passes on an electron to FAD which passes the electron on to FMN. FMN passes the electron on to the heme in the oxygenase domain on the opposite subunit. The oxygenase domain contains 5,6,7,8-tetrahydrobiopterin (H<sub>4</sub>B) and the already mentioned heme. These two are also redox active groups. Besides Heme and H<sub>4</sub>B, the oxygenase domain binds the substrate L-arginine which takes part in the NO synthase reaction (see below). | ||
Many structures of NOS have been determined. A list with additional information can be seen | Many structures of NOS have been determined. A list with additional information can be seen [[NOS structures | here]]. | ||
== The reaction of NOS == | == The reaction of NOS == | ||
