1. Chapter 26
Amino Acids Metabolism

2. 26.1 Biosynthesis of Amino Acids
Essential Amino Acids
Ile Leu Lys Met
Phe Thr Trp Val
The amino acids can be grouped together into six biosynthetic pathways depending on the intermediate from which they are derived.

3. TCA CYCLE
a-Ketoglutarate Oxaloacetate
Glu Asp
Gln Pro Arg Asn Met Thr Lys
a-Ketoglutarate Ile
family
( Glutamate family) Aspartate family

4. GLYCOLYSIS
3-Phosphoglycerate Pyruvate
Ser
Ala Val Leu
Cys Gly Pyruvate family
3-Phosphoglycerate
family
( Serine family)

5. PENTOSE PHOSPHATE
GLYCOLYSIS PATHWAY
Phosphoenolpyruvate
Erythrose 4-phosphate Ribose 5-phosphate
Phe Tyr Trp His
Phosphoenolpyruvate and Histidine
Erythrose 4-phosphate family
( Aromatic family)

6. 26.2 Amino Acid Degradation
The amino acids are degraded by 20 different pathways that converge to just 7 metabolic intermediates
Pyruvate
a-Ketoglutarate Succinyl-CoA
Fumarate Oxaloacetate
Acetyl-CoA Acetoacetate

7. Glucogenic
Ketogenic

8. deamination

9. transamination

11. 26.2.4 decarboxylation decarboxylase RCHNH2COOH RCH2NH2 + CO2
a-Amino Acid amine
Pyridoxyl Phosphate

12. 26.3 Ammonia Excretion Glucose-alanine cycle IN MUSCLE
NH4+ + a-Ketoglutarate + NADPH + H+
glutamate dehydrogenase
Glu + NADP+ + H2O
alanine transaminase
Glu + Pyruvate a-Ketoglutarate + Ala
IN LIVER
Ala + a-Ketoglutarate Pyruvate + Glu

13. The excess nitrogen is first converted into ammonia and is the excreted from living organisms in one of three ways.
Many aquatic animals simply excrete the ammonia itself directly into the surrounding water. Birds and terrestrial reptiles excrete the ammonia in the form of uric acid, while most terrestrial vertebrates convert the ammonia into urea before excretion.
These three classes of organisms are called: ammonotelic, uricotelic and ureotelic, respectively.

14. 26.4 The Urea Cycle Carbamoyl phosphate synthetase
Ornithine transcarbamoylase
Argininosuccinate synthetase
Argininosuccinase
Arginase

18. The overall reaction of the urea cycle
NH4+ + HCO3- + H2O + 3ATP + aspartate
urea + 2ADP + AMP + 2Pi + PPi + fumarate