The two nitrogen atoms that are incorporated into the urea cycle. The source of the nitrogen is
Glutamate & Aspaate
Aspaate & Arginine
Aspaate & NH3
Glutamate & NH3
Two nitrogen atoms of urea are derived from two different sources, one from ammonia and the other directly from alpha amino group of aspaic acid.Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 203
Metabolism of protein and amino acid