LE 4: Nitrogen Metabolism Reactions

transaminase/ aminotransferase, pyridoxal phosphate

amino acid + a-ketoglutarate —> a-keto acid + glutamate

alanine aminotranferase, pyridoxal phosphate

alanine + a-ketoglutarate —> pyruvate + glutamate

aspartate aminotransferase, pyridoxal phosphate

aspartate + a-ketoglutarate —> oxaloacetate + glutamate

glutamate dehydrogenase

glutamate + H2O —> a-ketoglutarate + +NH4

glutamine synthetase

L-Glutamate —> y-Glutamyl phosphate

glutamine synthetase

y-Glutamyl phosphate —> L-Glutamine

glutaminase (liver mitochondria)

L-glutamine —> L-glutamate

alanine aminotransferase

Glutamate —> a-Ketoglutarate

alanine aminotransferase

a-Ketoglutarate —> Glutamate

carbamoyl phosphate synthetase I

NH3 + CO2 —> carbonyl phosphate

ornithine transcarbamoylase

carbamoyl phosphate + ornithine —> citrulline

argininosuccinate synthetase

2nd aa enters between amino group + ureido group —> argininosuccinate

argininosuccinase

argininosuccinate —> arginine + fumarate

arginase

arginine —> urea + ornithine