How biology handles nitrite

Nitrite is one of the players in the broad nitrogen biogeochemical cycle. This nitrogen oxo-anion is involved in key pathways crucial to life on Earth and to the planetary recycling of nitrogen. The global aim is to review the present functional, structural, and mechanistic knowledge of nitrite reduction/oxidation, to assess in what extent we understand how nitrite is handled by living organisms. Nitrite formation is outside the scope of this Review. This knowledge is essential for the comprehension of the global nitrogen biochemical cycle and, consequently, for the comprehension of the impressive changes the human activities are introducing in the cycle. However, under most physiological conditions, glutamate dehydrogenase catalyzes instead the reverse reaction, yielding ammonium in amino acid catabolism.