AMINO ACID BIOSYNTHESIS

Amino acids are synthesized from the intermediates in Glycolysis and Krebs cycle.

Aminoacids and their respective Glycolysis/Krebs cycle intermediates are given below:

• Histidine is synthesized through from Glucose-6-posphate through Ribose-5-posphate.
• Serine, Glycine, Cysteine are synthesized from the common precursor 3-Posphoglycerate.
• Posphoenolpyruvate along with erythrose-4-posphate are the precursors for aromatic aminoacids viz., Phenylalanine, tryptophan, tyrosine.
• Alanine, Valine, Leucine, Isoleucine are synthesized from Pyruvate.
• Aspartate, Asparagine, methionine, threonine and Lysine are synthesized from Oxaloacetate.
• Glutamate, Glutamine, Arginine, Proline are aynthesized from alpha-Ketoglutarate

Histidine Synthesis:

PRPP, ATP, Glutamine are the 3 presursors in Histidine synthesis.

PRPP - Posphorybosyl pyroposphate

The addition of ATP to PRPP is catalysed by ATP Posphorybosyl transferase
L-Histidinol is converted to Histidine by Histidinol dehydrogenase

Serine, Glycine and Cysteine Synthesis :

The synthesis of Cysteine varies in bacteria, Plants and mammals.
Plants and animals produce reduced sulfur from sulfates in the environment. This reduced sulfur is used in the synthesis of Cystein, and Methionine ('sulfur conataining amino acids' ).

Mammals synthesize cysteine from two aminoacids, methionine and serine. Methionine provides the sulfur atom and serine provides the carbon skeleton.

I will Place the synthesis of remaining aminoacids in the next posts