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Amino acid catabolism

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


  • Transaminase (EC, EC Section 14.4E
  • Carbamoyl phosphate synthetase (EC P12. 4


Urea cycle:
  • Ornithine transcarbamylase (EC Section 12.2A,B*
  • Argininosuccinate synthetase (EC Section 12.6, Section 14.1D
  • Arginosuccinate lyase (EC Section 14.1D
  • Arginase (EC P12.16


Glycine  (glycine cleavage system)

  • Glycine dehydrogenase (decarboxylating) (EC P16.4b
  • Aminomethyltransferase (EC C11.5


Alanine (to pyruvate and glutamate):

  • Alanine transaminase (EC Section 14.4E



  • (to pyruvate): Serine dehydratase (EC Section 13.1B, Section 14.4F
  • (to glycine): Serine hydroxymethyltransferase (EC Section 11.6D, Section 14.4D


Cysteine (to pyruvate)

  • Cysteine dioxygenase (EC not covered
  • Aspartate aminotransferase ( Section 14.4E



pathway 1 (to glycine and acetyl CoA):

  • Threonine dehydrogenase (EC Section 16.4D*
  • Glycine C-acetyltransferase (EC Section 14.4D

pathway 2 (to glycine and acetaldehyde):

  • Threonine aldolase (EC Section 14.4D*, P14.10a

pathway 3 (to succinyl-CoA via propionyl CoA):

  • Threonine dehydratase (EC P14.2
  • 2-oxobutanoate dehydrogenase (EC Section 16.12B*
  • Propionyl-CoA carboxylase (EC Section 13.5D*, P13.2*
  • Methylmalonyl-CoA mutase (EC not covered


Tryptophan (to glutaryl-CoA)

  • Tryptophan 2,3-dioxygenase (EC not covered
  • Arylformamidase (EC Chapter 12*
  • Kynurenine 3-monooxygenase (EC Section 16.10
  • Kynurenimase (EC P14.10b
  • 3-hydroxyanthranilate 3,4-dioxygenase (EC not covered
  • Aminocarboxymuconate-semialdehyde decarboxylase (EC Section 13.5C*, P13.5a
  • 2-aminomuconate semialdehyde dehydrogenase (EC Section 16.4D*, P16.2a
  • 2-aminomuconate deaminase (EC Section 11.6*, P11.1
  • 2-oxoglutarate dehydrogenase (EC Section 16.12B*


Asparagine (to aspartate)

  • Asparaginase (EC Chapter 12*



  • (to oxaloacetate): Aspartate transaminase (EC Section 14.4E
  • (to fumarate): Aspartate-ammonia lyase (EC P14.3


Glutamine (to glutamate)

  • Glutaminase (EC Chapter 12


Glutamate (to alpha-ketoglutarate):

  • Glutamate dehydrogenase (EC Section 16.4D


Arginine (to glutamate):

  • Arginase (EC P12.16b
  • Ornithine transaminase (EC Section 14.4E*
  • Glutamate semialdehyde dehydrogenase (EC Section 16.4D


Histidine (to glutamate):


  • Histidine ammonia-lyase (EC C14.5
  • Urocanate hydratase (EC C16.1
  • Imidazolonepropionase (EC Chapter 12*
  • Formimidoylglutamase (EC P11.13b


Valine, isoleucine, leucine:

  • Branched chain amino acid transaminase (EC Section 14.4E*
  • Branched chain ketoacid dehydrogenase complex (EC Section 16.12B*
  • Acyl CoA dehydrogenase (eg. EC Section 16.5C, Section 17.3C

valine (to succinyl CoA):

  • Enoyl-CoA hydratase (EC P16.9
  • 3-hydroxyisobutyryl-CoA hydrolase (EC P16.9
  • 3-hydroxyisobutyrate dehydrogenase (EC P16.9
  • Methylmalonate-semialdehyde dehydrogenase ( P16.9
  • Propionyl-CoA carboxylase (EC Section 13.5D*, P13.2*
  • Methylmalonyl-CoA mutase (EC not covered

isoleucine (to succinyl CoA and acetyl CoA):

  • Enoyl-CoA hydratase (EC P16.9
  • Methyl-hydroxybutyryl CoA dehydrogenase (EC Section 16.4*
  • 3-ketoacyl-CoA thiolase (EC Section 13.4B*
  • Propionyl-CoA carboxylase (EC Section 13.5D*, P13.2*
  • Methylmalonyl-CoA mutase (EC not covered

leucine (to acetyl CoA)

  • Methylcrotonoyl-CoA carboxylase (EC Section 13.5*
  • Methylglutaconyl-CoA hydratase (EC Section 14.1*
  • Hydroxymethylglutaryl-CoA lyase (EC Section 13.3C*


Methionine (to cysteine and succinyl-CoA):

  • Methionine adenosyltransferase (EC E9.1
  • Methyltransferase (eg. Section 9.1A
  • Adenosylhomocysteinase (EC Section 14.1A
  • Cystathionine beta-synthase (EC Section 14.4G*
  • Cystathionine gamma-lyase (EC Section 14.4G
  • 2-oxobutanoate dehydrogenase (EC Section 16.12B*
  • Propionyl-CoA carboxylase (EC Section 13.5D*, P13.2*
  • Methylmalonyl-CoA mutase (EC not covered


Lysine (to glutaryl-CoA)

  • Saccharopine dehydrogenase (EC P11.6, P16.7a
  • Saccharopine reductase (EC P11.7, P16.7b
  • Aminoadipate-semialdehyde dehydrogenase (EC Section 16.4D*
  • 2-aminoadipate transaminase (EC2.6.1.39) Section 14.4E*
  • 2-oxoglutarate dehydrogenase (EC Section 16.12B*


Phenylalanine (to tyrosine):

  • Phenylalanine hydroxylase (EC not covered


Tyrosine (to fumarate and acetoacetate):

  • Tyrosine transaminase (EC Section 14.4E*
  • 4-hydroxyphenylpyruvate dioxygenase (EC not covered
  • Homogentisate 1,2-dioxygenase (EC not covered
  • Maleylacetoacetate isomerase (EC Section 14.2A*
  • Fumarylacetoacetase (EC Section 13.4B*