Nitrogen Metabolism An Overview

Atmospheric nitrogen (Ng) is not highly reactive, but it must be converted to ammonia or to nitrates to be biologically useful, first to plants, then to animals. 

Nitrogen compounds in the biosphere include amino acids, purines, and pyrimidines. Their pathways for biosynthesis and breakdown tend to be long and complex. 

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The topic of nitrogen metabolism includes the biosynthesis and breakdown of amino acids, purines, and pyrimidines also, the metabolism of porphyrins is related to that of amino acids. Many of these pathways, particularly the anabolic ones, are long and complex. In discussing pathways in which the amount of material is large and highly detailed, we shall concentrate on the most important points. Specifically, we shall concentrate on overall patterns and on interesting reactions of wide applicability. We shall also be interested in health-related aspects of this material. Other reactions will be found at the BiochemistryNow Interactive website for this text. It can be considered a repository of supplementary material for this chapter, and we shall refer to it a number of times. 

Root nodules of leguminous plants play a pivotal role in nitrogen fixation. 

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