Nitric-oxide synthase (NOS; EC 184.108.40.206) catalyzes the oxidation of L-arginine to nitric oxide (NO.) and L-citrulline via the intermediate Nω-hydroxy-L-arginine. Of the three distinct isoforms of NOS that have been characterized, the constitutive neuronal NOS (NOS I) generates NO. associated with long-term potentiation (LTP) and early brain development. All of the NOS isoforms contain an N-terminal oxidase and a C-terminal reductase domain connected by a Ca2+/calmodulin binding region. To activate NOS I, Ca2+ has to bind to calmodulin, allowing electron transport through both domains. Calcium ions are tightly regulated in cells. However, a number of other metal ions that bind and activate calmodulin may also activate NOS I. One such metal ion may be Pb2+, which is associated with neurobehavioral and psychological alterations, including the inhibition of LTP. The effect of various divalent cations on NOS I activity was tested, and the results presented herein demonstrate that Pb2+ and Sr2+ can activate NOS I to a level similar to that found for Ca2+. Finally, there is a synergy between Pb2+ and Ca2+ resulting in maximal activation of NOS I using minimal concentrations of both metal ions.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Pharmacology and Experimental Therapeutics|
|State||Published - 2002|
ASJC Scopus subject areas
- Molecular Medicine