I. Amino-acid Nitrogen Removal by
Transamination and its Utilization for Urea
1) An amino acid and an oxo- (keto-) acid
2) Vitamin pyridoxol
3) An aminotransferase.
The oxoacid can be either
pyruvate, which produces alanine,
oxaloacetate, which produces aspartate
2-oxoglutarate, which produces glutamate
Transamination with 2-oxoglutarate is important because this reaction allows an amino acid nitrogen to become the nitrogen of ammonia.
When the nitrogen of an amino acid is not needed for growth and maintenance it is excreted in the form of urea.
Urea is synthesized by the Urea Cycle.
The first and rate-determining step requires ammonia.