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Amino acid biosynthesis

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Sections/problems listed with an asterisk (*) do not discuss the exact reaction indicated, but do discuss a closely related reaction.


Alanine (from pyruvate)


Aspartate (from oxaloacetate):


Glutamate (from alpha-ketoglutarate)


Glutamine (from glutamate)


Asparagine (from aspartate)


Arginine (from glutamate via ornithine, urea cycle)

to arginine via urea cycle:


Proline (from glutamate)


Serine (from 3-phosphoglycerate)


Cysteine (from serine)

or, in bacteria:


Glycine (from serine)


Lysine (from aspartate)


Methionine (from aspartate via homoserine)


Threonine (from homoserine)


Isoleucine, leucine, and valine (from pyruvate):

to isoleucine:

  • Branched-chain-amino-acid aminotransferase (EC Section 14.4E*

to valine:

  • Valine—pyruvate aminotransferase (EC Section 14.4E*

to leucine:

  • 2-isopropylmalate synthase (EC Section 13.3*
  • Isopropylmalate isomerase (EC P14.7
  • 3-isopropylmalate dehydrogenase (EC Section 16.4*
  • Leucine aminotransferase (EC Section 14.4E*


Aromatic amino acids

Erythrose-4-phosphate to chorismate:

  • DAHP synthase (EC Section 15.2C
  • Dehydroquinate synthase (EC C13.1, 14.1A
  • Dehydroquinate dehydratase (EC Section 14.1D
  • Shikimate dehydrogenase (EC Section 16.4*
  • Shikimate kinase (EC P10.2 Section 10.2*
  • 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase (EC Section 14.3B, Section 15.4
  • Chorismate synthase (EC Section 14.3B, Section 17.3C

chorismate to tryptophan:

  • Anthranilate synthase (EC P14.8a
  • Anthranilate phosphoribosyltransferase (EC Section 11.5*
  • Phosphoribosyl anthranilate isomerase (EC P11.12, P13.12
  • Indole-3-glycerol phosphate synthase (EC Section 15.5B
  • Tryptophan synthase (EC Section 13.3C, E13.7, Section 15.5B

chorismate to phenylalanine/tyrosine:

  • Chorismate mutase (EC Section 15.10
  • Prephenate decarboxylase (EC Section 14.3B
  • Aromatic-amino-acid aminotransferase (EC Section 14.4E*
  • Tyrosine aminotransferase (EC Section 14.4E*



  • ATP phosphoribosyltransferase (EC  Section 11.5*
  • Phosphoribosyl-ATP diphosphatase (EC 3..6.1.31) Section 10.3*
  • Phosphoribosyl-AMP cyclohydrolase (EC P12.12
  • 1-(5-phosphoribosyl)-5-[(5-phosphoribosylamino)methylideneamino]imidazole-4-carboxamide isomerase (EC P14.8b
  • Imidazole glycerol-phosphate synthase (no EC number assigned) Section 11.6*, C11.1
  • Imidazoleglycerol-phosphate dehydratase ( Section 14.3B
  • Histidinol-phosphate transaminase (EC Section 14.4E*
  • Histidinol-phosphatase (EC Section 10.3*
  • Histidinol dehydrogenase (EC Section 16.4D*