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How does the body biosynthesize the non-essential amino acids and what are the chemical reactions involved?

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The human body can biosynthesize non-essential amino acids through various metabolic pathways and chemical reactions. Non-essential amino acids are those that the body can produce on its own, and they include alanine, asparagine, aspartic acid, glutamic acid, glutamine, glycine, proline, serine, and cysteine. Here, we will discuss the biosynthesis of some of these non-essential amino acids and the chemical reactions involved.1. Alanine: Alanine is synthesized through the transamination of pyruvate, which is a product of glycolysis. The enzyme alanine aminotransferase  ALT  catalyzes the transfer of an amino group from glutamate to pyruvate, forming alanine and -ketoglutarate.Reaction: Pyruvate + Glutamate  Alanine + -Ketoglutarate2. Asparagine: Asparagine is synthesized from aspartate through the action of asparagine synthetase. This enzyme catalyzes the transfer of an amino group from glutamine to aspartate, forming asparagine and glutamate.Reaction: Aspartate + Glutamine  Asparagine + Glutamate3. Aspartic acid: Aspartic acid is synthesized through the transamination of oxaloacetate, which is an intermediate in the citric acid cycle. The enzyme aspartate aminotransferase  AST  catalyzes the transfer of an amino group from glutamate to oxaloacetate, forming aspartate and -ketoglutarate.Reaction: Oxaloacetate + Glutamate  Aspartate + -Ketoglutarate4. Glutamic acid: Glutamic acid is synthesized through the transamination of -ketoglutarate, which is an intermediate in the citric acid cycle. The enzyme glutamate dehydrogenase catalyzes the transfer of an amino group from an ammonium ion to -ketoglutarate, forming glutamate.Reaction: -Ketoglutarate + NH4+  Glutamate5. Glutamine: Glutamine is synthesized from glutamate through the action of glutamine synthetase. This enzyme catalyzes the addition of an ammonium ion to glutamate, forming glutamine.Reaction: Glutamate + NH4+  Glutamine6. Glycine: Glycine is synthesized from serine through the action of the enzyme serine hydroxymethyltransferase. This enzyme catalyzes the transfer of a hydroxymethyl group from serine to tetrahydrofolate, forming glycine and 5,10-methylenetetrahydrofolate.Reaction: Serine + Tetrahydrofolate  Glycine + 5,10-Methylenetetrahydrofolate7. Proline: Proline is synthesized from glutamate through a series of reactions. First, glutamate is converted to glutamate semialdehyde, which is then cyclized to form pyrroline-5-carboxylate. Finally, pyrroline-5-carboxylate is reduced to proline.Reaction steps:a. Glutamate  Glutamate semialdehydeb. Glutamate semialdehyde  Pyrroline-5-carboxylatec. Pyrroline-5-carboxylate  Proline8. Serine: Serine is synthesized from 3-phosphoglycerate, which is an intermediate in glycolysis. First, 3-phosphoglycerate is converted to 3-phosphohydroxypyruvate, which is then reduced to form phosphoserine. Finally, phosphoserine is dephosphorylated to form serine.Reaction steps:a. 3-Phosphoglycerate  3-Phosphohydroxypyruvateb. 3-Phosphohydroxypyruvate  Phosphoserinec. Phosphoserine  Serine9. Cysteine: Cysteine is synthesized from serine and homocysteine through the action of the enzyme cystathionine -synthase. This enzyme catalyzes the transfer of a sulfur atom from homocysteine to serine, forming cystathionine. Cystathionine is then cleaved by the enzyme cystathionine -lyase to form cysteine.Reaction steps:a. Serine + Homocysteine  Cystathionineb. Cystathionine  CysteineThese biosynthetic pathways and chemical reactions allow the human body to produce non-essential amino acids, which are crucial for protein synthesis and various other metabolic processes.
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