NÎTRÎK OKSÎTİN SENTEZİ VE BİYOLOJİK ÖNEMİ

Yalnızca atmosferde kirlenmeye neden olduğu düşünülen nitrik oksit gazının, memeli hücreleri tarafından üretildiğinin anlaşılmasından sonra bir çok biyolojik olay hakkında önemli bilgiler elde edilmiştir. Nitrik oksit NO , arginin aıninoasitinden sitrüilin şekillenmesi sırasmda Nitrik oksit sentaz NOS enzimi aracılığıyla sentezlenir. NOS’ın farklı genler tarafından kodlanan üç izoformu vardır: Uyarılabilir NOS İNOS , makrofajlarda tümör ve bakteri hücrelerini öldürmek, damar endotel hücrelerinde bulunan endotelyal NOS eNOS ise kan damarlarının gevşemesi için, sinir hücrelerinde lokalize olan nöronal NOS nNOS da nörotransmiter olarak NO üretir. eNOS ve nNOS, kalsiyum ile kalmoduline bağlıdır. Reseptörlerin uyarılması için pikomol miktarlarda NO sentezler. Bununla beraber İNOS kalsiyumdan bağımsızdır ve nanomol düzeyinde NO üretir. NOS, L-arginin analogları tarafından inhibe edilir

Anahtar Kelimeler:

Arginin, Nitrik oksit, Nitrik oksit sentaz

BİOLOGİCAL ACTİVİTY AND SYNTHESİS OF NİTRİC OXİDE

zThe understand that mammalian cells generate nitric oxide NO , a gas previously thought to be only an atmospheric pollutant, is providing important information about many biological process. NO is formed by nitric oxide synthase NOS oxidizing arginine to NO with the formation of citrulline. Three distinct gene codes for the three forms of NOS: inducible NOS İNOS , whose induced synthesis enables macrophages to form the NO that kills tumor cells and bacteria, endothelial NOS eNOS , which produces the NO that relaxes blood vessels, and neuronal NOS nNOS , which as neurotransmitter. İNOS and nNOS are calcium and calmodulin-depent, andrelease picomoles of nitric oxide in response to receptor stimulation. However İNOS is calcium-independent and release nanomol of nitric oxide. NOS is inhibited by L-arginine analogues

Keywords:

Arginine, Nitric oxide, Nitric oxide synthase,

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