BIOSYNTHESIS AMINO ACIDS

BIOSYNTHESIS AMINO ACIDS

• Amino acids are organic compounds containing Amine functional group (-NH₂) and Carboxyl (COOH) functional groups, along with a side chain(R group).
• Nutritionally Amino acids are classified into three types. They are

1)    Essential Amino acids

2)    Non-essential Amino acids

3)    Semi-essential Amino acids

1)   Essential Amino Acids (or) Indispensable Amino acids

Essential Amino acids are the amino acids which are not synthesized by the body and must be taken in diet. The list of eight Essential amino acids includes: (i) Valine, (ii) Isoleucine, (iii) Leucine, (iv) Lysine, (v) Methionine, (vi) Phenylalanine, (vii) Threonine and (viii) Tryptophan. The dietary importance of Essential Amino Acids was first described by William Cumming Rose.

2)   Non – essential Amino acids (or) Dispensable Amino acids

Non-essential Amino acids are the amino acids which are synthesized by the body and must not be taken in diet. The list of ten Non-essential amino acids includes: (i) Glycine, (ii) Alanine, (iii) Serine, (iv) Cysteine, (v) Aspartate, (vi) Asparagine, (vii) Glutamate, (viii) Glutamine, (ix) Tyrosine and (x) Proline.

3)   Semi – essential Amino acids

Semi-essential Amino acids are the amino acids which are synthesized by adults and not by growing children. These includes (i) Arginine and (ii) Histidine.

Biosynthesis of Amino acids

• Amino acids are required for Protein biosynthesis.
• Some microbes, such as Escherichia coli, contain the enzymes necessary to use starting materials, such as Glucose and inorganic salts, for the synthesis of all the amino acids they need.
• Organisms with the necessary enzymes can synthesize all Amino acids directly or indirectly from intermediates of Carbohydrate metabolism.
• All amino acids are derived from intermediates in Glycolysis, the Citric acid cycle, or the Pentose phosphate pathway.
• One important source of the Precursors (intermediates) used in Amino acid synthesis is the Krebs cycle. Adding an Amine group to Pyruvic acid or to an appropriate organic acid of the Krebs cycle converts the Acid into an Amino acid. This process is called Amination.
• If the Amine group comes from a preexisting amino acid, the process is called Transamination.

Biosynthesis of Amino acids