41. Other Ways of Detoxification of Ammonia: Reductive Amination, Oxidative Deamination of Amino Acids, The Role Of Glutamate, Biosynthesis of Glutamine. The Role of Renal Glutaminase.
Explains how the body keeps ammonia from building up by routing it into safer forms. It takes reductive amination via glutamate dehydrogenase, oxidative deamination that releases ammonia for urea synthesis, and the central role of glutamate as an amino group carrier. It then covers glutamine synthesis as a non-toxic transport form and the renal glutaminase system that excretes ammonium to help control acid-base balance, ending with brief clinical takeaways on hyperammonaemia and acidosis.
Topic 41 of 76 in the MU Pleven syllabus for Biochemistry (Medicine, Year 2). The free AceMed note covers it in 3 sections, about 358 words (3 min of reading), with 20 flashcards.
In this note
Other Ways of Detoxification of Ammonia: Reductive Amination, Oxidative Deamination of Amino Acids, The Role Of Glutamate, Biosynthesis of Glutamine.
Other Ways of Detoxification of Ammonia
Key Clinical Takeaways
Other Ways of Detoxification of Ammonia
The body cannot allow free ammonia (NH₃) to accumulate, because it is highly neurotoxic.
So ammonia is re-routed, chemically modified, and transported in safe forms.
The major systems involved:
Reductive amination
Oxidative deamination
Transamination and role of glutamate
Formation of glutamine
Renal glutaminase system
1. Reductive Amination
Mediated by Glutamate Dehydrogenase (GDH) in mitochondria.
Reaction:
α-Ketoglutarate + NH₃ + NADPH → Glutamate.
This reaction captures free ammonia and stores it safely as glutamate.
Occurs mostly in the liver and brain.
Helps prevent ammonia accumulation.
2. Oxidative Deamination of Amino Acids
Also catalyzed primarily by Glutamate Dehydrogenase (GDH).
Reaction:
Glutamate → α-ketoglutarate + NH₃.
This mainly occurs in the liver mitochondria.
It frees ammonia only when there is a need to convert it into urea.
Thus oxidative deamination provides NH₃ for the urea cycle.
3. The Central Role of Glutamate
Glutamate is the main “traffic hub” of amino group metabolism.
It is formed by transamination of most amino acids.
