View source for Basic reactive forms of oxygen and nitrogen

== Reactive Nitrogen Species (RNS) ==
{| class="wikitable"
 |+ 
 ! Free nitrogen radicals !! substances that are not free radicals
 |- 
 | nitric oxide (NO•) || Nitrosyl (NO<sup>+</sup>)
 |-
 | nitrogen dioxide (NO<sub>2</sub>•) || nitrous oxide (NO)
 |-
 |  || Peroxynitrite (ONOO<sup>−</sup>)
 |-
 |  || Alkylperoxynitrite (ROONO)
|}

=== Nitric oxide NO ===

<big>'''NO:'''</big> {{Video | url=https://youtu.be/pPAt6kXc90c?t=54}}

Gaseous radical with a short biological half-life. When inhaled, it is toxic (smog) to the body. Inside the body, it is created physiologically as a mediator (eg vasodilation). By binding to guanylate cyclase, it stimulates cGMP production leading to smooth muscle relaxation. It has a high '' affinity '''for heme iron''' ''. It is'' '''taken up by erythrocytes''', in which it reacts with hemoglobin to form methaemoglobin and nitrate (physiological inactivation of NO).''

==== Origin in the organism ====
'''NO synthase reaction'''

L-arginin + O<sub>2</sub> + NADPH → L-citrullin + NADP<sup>+</sup> + NO•

We distinguish three different synthases, which differ according to the site of action. '' '''NOS I''' ''(neuronal, constitutive) - memory and learning, '' '''NOS II''''' (phagocytes, inducible) - stimulated by cytokines and microbes, '' '''NOS III''' '' (endothelial, constitutive) - vasodilatory effect.

==== Reaction ====
'''Reactions with superoxide'''

During the reaction of NO • se • O <sub> 2 </sub> <sup> - </sup>, '' '''peroxynitrite''' '' is formed, which is the most important toxic product of nitric oxide.

NO • + • O <sub> 2 </sub> <sup> - </sup> → OONO <sup> - </sup> (peroxynitrite)

Peroxinitrite is the '''most powerful producer of free radicals''''' in cells.''

OONO <sup> - </sup> + H <sup> + </sup> → HOONO (peroxynitric acid) → OH • + • NO <sub> 2 </sub>