Metabolism of ammonia

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

1. Metabolism of Ammonia
Dr. RohiniC Sane

2. MetabolismofAmmonia
NH3 → NH4 ⁺ ion ( exist ammonium ion at p H 7.4)
I .FormationofAmmonia:
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
Efficienttransport&immediate utilization of ammonia for urea
synthesis
Ammonia is transported as Glutamine & Alanine (Glucose –Alanine cycle
No freeAmmonia 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
SymptomsofToxicity of Ammonia
•Marginal elevation –toxic to brain
•Slurring of speech
•Blurring of vision
•Tremors
•Coma
•Death
Biochemistry of Toxicity of Ammonia
NH3 ↑
↓
GLUTAMATE ↑
↓
αKGA (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
Arginosucdefectiveencinate
synthtase
HYPER AMMONEMMIA IV
Arginosuccinicaciduria
Arginosuccinase
HYPER AMMONEMMIA V
Hyperargininemia
Arginase