A comprehensive presentation on Metabolism of Ammonia for MBBS, BDS ,B.Pharm & Biotechnology students to facilitate self study.

1. Metabolism of Ammonia
Dr. Rohini C Sane

2. Metabolism of Ammonia
NH3 → NH4 ⁺ ion ( exist ammonium ion at p H 7.4)
I .Formation of Ammonia :
a ) Transamination & Deamination of biogenic amines ,NH2 group of
Purines & Pyrimidine
b) Urea  bacterial urease  NH3
II . Transport & storage :
Conc of serum ammonia  10 -20 micro gram /dl
Efficient transport &immediate utilization of ammonia for urea
synthesis
Ammonia is transported as Glutamine & Alanine (Glucose –Alanine cycle
No free Ammonia in serum under physiological conditions

5. Functions of Ammonia
Waste products of nitrogen
Synthesis of compounds like
a) Non essential amino acids
b) Purines
c) Pyrimidine
d) Amino sugars
e) Asparagine
f) NH₄⁺(acid base balance )

6. PURINE BASE

7. Disposal of Ammonia
1) Ammonitelic : ammonia excreted in water eg aquatic animals
2) Uricotelic : ammonia excreted as uric acid eg reptiles & birds
3) Ureotelic : ammonia excreted as urea (non toxic ,water soluble )eg mammals
AMMONIA URIC ACID
UREA

8. Toxicity of Ammonia
Symptoms of Toxicity of Ammonia
• Marginal elevation –toxic to brain
• Slurring of speech
• Blurring of vision
• Tremors
• Coma
• Death
Biochemistry of Toxicity of Ammonia
NH3 ↑
↓
GLUTAMATE ↑
↓
α KGA (intermediate of TCA CYCLE ) ↓
↓
TCA ( impairment of TCA ) ↓
↓
ATP in brain ↓

9. Hyperammonemia
(a) Genetic defects in enzymes of Urea cycle (neonates )
↓
Mental retardation
(b) Acquired Hepatitis ( alcoholism- defective urea synthesis )

10. Metabolic disorders of Urea cycle
Type of Hyperammonemmia Defective Enzyme
HYPER AMMONEMMIA I CPS I
HYPER AMMONEMMIA II Ornithine Trans carbomylase
HYPER AMMONEMMIA III
Citullinemia
Argino sucdefective encinate
synthtase
HYPER AMMONEMMIA IV
Arginosuccinic aciduria
Arginosuccinase
HYPER AMMONEMMIA V
Hyperargininemia
Arginase