Inhibition of mammalian nitric oxide synthases by agmatine, an endogenous polyamine formed by decarboxylation of arginine
1996; Portland Press; Volume: 316; Issue: 1 Linguagem: Inglês
10.1042/bj3160247
ISSN1470-8728
AutoresElena Galea, S. Regunathan, Vassily ELIOPOULOS, Douglas L. Feinstein, Donald J. Reis,
Tópico(s)Neuroendocrine regulation and behavior
ResumoAgmatine, decarboxylated arginine, is a metabolic product of mammalian cells. Considering the close structural similarity between L-arginine and agmatine, we investigated the interaction of agmatine and nitric oxide synthases (NOSs), which use L-arginine to generate nitric oxide (NO) and citrulline. Brain, macrophages and endothelial cells were respectively used as sources for NOS isoforms I, II and III. Enzyme activity was measured by the production of nitrites or L-citrulline. Agmatine was a competitive NOS inhibitor but not an NO precursor. Ki values were approx. 660 microM (NOS I), 220 microM (NOS II) and 7.5 mM (NOS III). Structurally related polyamines did not inhibit NOS activity. Agmatine, therefore, may be an endogenous regulator of NO production in mammals.
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