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Each amino transferase is specific for one or at most a few amino group donors. Amino transferases are named after the specific amino group donors because the acceptor of the amino acid is almost always α-ketoglutarate. The most important amino transferase reactions are catalysed by alanine amino transferase or serum glutamate pyruvate transaminase (SGPT) and…

Figure 9.3 Transamination Reaction

Transamination is defined as the transfer of amino group (—NH2) from an amino acid to keto acid. This process entails the inter-conversion of a pair of amino acids and a pair of keto acids catalysed by a group of enzymes known as transaminases (amino transferases) as shown in Figure 9.3.

INTRODUCTION The amino acid obtained from dietary source or body protein turnover is utilised for protein biosynthesis and the production of a wide range nitrogen-containing compounds (creatine, amines, phorphyrin, and so on). The amino parts of amino acid are utilised for the biosynthesis of urea; the remaining carbon skeletons are converted to various intermediates of…

Animals which excrete urea as the major excretory product are said to be ureotelic. Urea is a useful product for a semi-terrestrial animal that is not exposed to scarcity of water but is not necessarily surrounded by large quantities of it. It is, therefore, the main product of some earthworms, shore gastropods, adult amphibians, and…

Animals which excrete their nitrogen predominantly in the form of uric acid are called uricotelic. All genuinely terrestrial animals, including insects, terrestrial gastropods, terrestrial reptiles (snakes and lizards), and birds excrete mainly uric acid. Insects and land snails excrete solid pellets of uric acid, whereas reptiles and birds void a thick paste of uric acid…

Animals which excrete their nitrogenous wastes as ammonia are said to be ammonotelic. Excretion of ammonia, which is presumed to be the primitive material, is especially suited to an aquatic habit. Ammonia is highly soluble in water, with which it forms ammonium hydroxide (NH4OH). The latter passes readily across the cell membranes and is dispersed…