The document discusses transamination and deamination processes, detailing the roles of enzymes, cofactors, and the significance of these pathways in amino acid metabolism. It highlights the mechanisms of transamination involving pyridoxal phosphate and the simultaneous occurrence of transamination and deamination. Additionally, the document covers the oxidative deamination of amino acids by specific enzymes, the regulation of these processes, and their contributions to energy production and the synthesis of non-essential amino acids.

1. Transamination & Deamination
Dr Rohini C Sane

2. Transamination
Definition : Transfer of amino group to keto acids
1. Transaminases ( amino transferase)
2. amino acids 1+ α keto acids 1↔ amino acids 2+ α keto acids 2
3. Pyridoxal phosphate –cofactor derived from vitamin B6
4. No free ammonia
5. Reversible ( catabolism /anabolism )
6. Excess amino acids derived used for energy generation
7. Synthesis of non essential amino acids /redistribution of amino group
8. Lysine / Threonine/ Proline / hydroxyl proline  exception to rule
9. Production of non essential amino acids
10 . α amino acids / δ amino acids ( Ornithine ) undergo transamination
11. Clinical significance : SGOT ↑ in AMI & SGPT ↑IN Liver diseases
.

3. TRANSAMINATION

4. ROLE OF PYRIDOXAL PHOSPHATE IN TRANSAMINATION

6. TRANSAMINATION

7. TRANSAMINATION BY SGPT

8. TRANSAMINATION BY SGOT

11. Mechanism of Transamination
• CHO group of PLP forms Schiff base (1 )with Lys residue of transaminase
with imine linkage
Lys displaced by amino acid to form Schiff base (2 )

13. Deamination
• Definition : Removal of amino group as ammonia which is utilized for urea
formation & carbon skeletons are used for formation the keto acids .
• Transamination & Deamination take place simultaneously.(Trans deamination )

14. Fate of carbon skeletons of amino acids
1. Oxidation  TCA  Energy
2. Synthesis of Glucose
3. Formation of lipids ( fatty acids & ketone bodies )
4. Synthesis of non essential amino acids

15. Entry points of amino acids in TCA cycle
Amino acids Entry points of amino acids in TCA cycle
Ala ,Gly , Cyst ,Ser, Thr Pyruvate, Acetyl CoA
Phe, Tyr ,Trp ,Leu ,Lys ,Ile Aceto- acetate
Asn, Asp Oxaloacetate
His, Arg, Pro ,Glu ,Gln α KGA
Met, Val ,Ile,Thr Succinyl Co A

16. Oxidative Deamination
1. Site : kidney & Liver ( mitochondria )
2. Catalyzed by Glutamate dehydrogenase ( GDH )
Purpose :/significance
a) Ammonia utilized for  Urea formation
b) α keto acids for energy
c) Glutamate accepts amino group from amino acids ( Transamination )
d) Glutamate –is collection center for amino group oxidative deamination

17. Oxidative deamination by Glutamate dehydrogenase (GDH )
TCA CYCLE

18. Regulation of Glutamate dehydrogenase (GDH )
1. protein rich diet  ↑ GDH Glutamate concentration increases in liver
concentration of α KGA increases concentration of NH3 increases
TCA increases ( ↑ ATP ) Urea production increases
2. Steroid hormones / Thyroid hormones ↓ GDH
3. Cellular energy low  Glutamate ↓  oxidative deamination induced ↑ GDH
4.Allosteric Regulation of Glutamate dehydrogenase (GDH )
Allosteric inhibitors Allosteric activators
GTP GDP
ATP ADP
Glutathione
GABA
N ACETYL GLUTAMATE (NAG )

21. Oxidative deamination of Amino acid oxidases
Reduction of O2 to H2O2  hydrolysis to water

22. Oxidative deamination by Amino acid oxidases
• Activity of L -amino acid oxidases low
• Activity of D amino acid oxidase high ( liver & kidney )
• L -amino acid oxidases dose not act on Glycine & di carboxylic acids
• L -amino acid oxidases dose appear to play significant role in amino
acid metabolism.

23. Oxidative deamination by Amino acid oxidases
D - amino acids (dietary/ plants / micro organisms /mammals )
H2O FAD
NH4 FADH2
Energy ←α Keto acids    glucose /fat conversion of unnatural
L amino acid Transaminase D amino acid  L amino acid
α Keto acids
L –amino acid
Metabolism

25. Non- oxidative deamination
• Amino acids deaminated to liberate ammonia without undergoing
oxidation
Serine Dehydratase
Threonine respective α keto acids
Homoserine PLP
( hydroxy amino acid ) NH3

26. Non- oxidative deamination by De sulphhydratases
cysteine Deamination
Homocystein PYRUVATE
Desulphhydration
NH3 + H2S

27. Non- oxidative deamination Histidine
Deamination
Histidine Urocanate
Histadase
NH3