How Biology Handles Nitrite

Abstract

Introduction 5273 2. Biological Fate of Nitrite 5274 2.1. Biological Fate of Nitrite − Nitrite in the Nitrogen Cycle 5274 2.1.1. Classic and New Pathways 5274 2.1.2. Nitrite and Nitrogen "Recycling" 5277 2.2. Biological Fate of Nitrite − Nitrite in Signaling Pathways 5277 2.2.1. Nitrite in Signaling Pathways in Mammals 5277 2.2.2. Nitrite in Signaling (and Other) Pathways in Plants 5297 2.2.3. Nitrite in Signaling (and Other) Pathways in Bacteria 5303 3. Biological Mechanistic Strategies To Handle Nitrite 5305 3.1. Nitrite Reduction to Ammonium 5306 3.1.1.

The Production of Ammonia by Multiheme Cytochromes c

“…It has a pyramidal shape, with an H-N-H angle of 106.7 (compared to 93.3 in phosphane, PH 3 ), and contains a single lone pair of electrons. Ammonia has a dipole moment of 1.47 D (compared to 0.57 D for PH 3 ). The solubility of ammonia in water is greater than that of any other gas because of hydrogen bond formation between NH 3 and H 2 O.…”

“…The equipment for the industrial production of ammonia was developed by the engineer, Carl Bosch, so the process is called the Haber-Bosch process. Historically and practically, it is closely associated with the Ostwald process in providing its requisite raw material, NH 3 . Unfortunately, the amount of reactive nitrogen entering the environment has significantly increased as a result, leading to a host of ecological problems [29,30].…”

“…Nitrogen is a basic element for life because it is a component of essential biomolecules, such as amino acids, proteins, and nucleic acids. In the biosphere, nitrogen exists in several oxidation states, ranging from +5 as in the nitrate anion (NO À 3 ) to À3 as in ammonia (NH 3 ; IUPAC name azane), and the ammonium cation, NH þ 4 . Interconversions of the various nitrogen species constitute the global biogeochemical nitrogen cycle, which is sustained by biological processes with microorganisms playing a predominant role ( Figure 1) [8].…”

“…It is a source of nitrogen for assimilation into organic nitrogen compounds by nitrate (and nitrite) ammonification according to equation (3) followed by incorporation of ammonia into biomass ( Figure 1). The same series of reactions, though usually catalyzed by distinct enzymes, can also occur as part of an anaerobic nitrate/nitrite respiration process in various bacteria, whereby nitrate and nitrite serve as terminal electron acceptors [1,3,18]. In this chapter we will briefly discuss the role of ammonia in the environment (Section 2) and subsequently summarize recent advances in the field of microbial ammonia production and consumption in relation to energy metabolism (Sections 3, 4, and 5).…”

“…Finally, the emerging picture of the role of multiheme cytochromes c in natural habitats and in microbial ecology is presented (Section 6). In view of the huge amount of data accumulating in the field, we recommend comprehensive reviews as primary references [3,[19][20][21][22][23][24][25].…”