Nitrogen Metabolism

Abstract

Publisher Summary This chapter provides an overview of nitrogen metabolism. It describes the biosynthesis of amino acids in plants and microorganisms, and in mammals and humans. Degradation of amino acids in microorganisms and plants is a rare event, but is of major importance in animals and humans. In man and mammals, the ammonium ions are converted into urea in the liver. The form in which amino nitrogen is excreted from the organism is dependent upon the adaptation of the organism to its habitat. In terms of amino nitrogen excretion, the animal kingdom can be classified into ammonotelic (ammonia), ureotelic (urea), and uricotelic (uric acid) organisms depending on the nature of the discharged substance. Urea is produced as a nontoxic soluble vehicle for the elimination of nitrogen originating from the catabolism of amino acids. A major function of the liver is urea biosynthesis, but enzymes of the pathway also occur in kidney, skin, brain plus some other cells where their primary purpose is to synthesize arginine. The chapter also discusses the biosynthesis of heterocyclic compounds, the hybridoma technique, and the degradation of heterocyclic compounds.