Principles of Biochemistry (2+1)

3.4.1.5.Amino acid metabolism

            Much of amino acid metabolism involves transamination.The amino acids are necessary for protein synthesis. Some must be supplied specifically in the diet (the essential amino acids), since the tissues are unable to synthesize them. The remainder, or nonessential amino acids, are also supplied in the diet, but they also can be formed form intermediates by transamination  using the amino nitrogen from other surplus amino acids. After deamination, excess amino nitrogen is removed as urea, and the carbon skeletons that remain after transamination(1)are oxidized to CO₂ via the citric acid cycle, (2) form glucose (gluconeogenesis), or (3) form ketone bodies.

       In addition to their requirement for protein synthesis, the amino acids are also the precursors of many other important compounds, eg, pruines, pyrimidines, and hormones such as epinephrine and thyroxine.

                               Fig.3.4.1.5.1.Amino acid metabolism