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Amino Acid Metabolism.

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Presentation on theme: "Amino Acid Metabolism."— Presentation transcript:

1 Amino Acid Metabolism

2 Role of Amino Acids Protein monomeric units Energy source
Precursors of other biological molecules

3 Protein Monomeric Units

4 Energy Source

5 Precursors (Nitrogen-containing Compounds)
Heme Nucleotides Amines Nucleotide Coenzymes Glutathione

6 Precursors (a-ketoacids)

7 Classification (Mammals)
Essential amino acids Non-essential amino acids

8 Amino Acid Deamination (First Reaction in Amino Acid Breakdown)

9 Aminotransferases (Transaminases)

10 Oxidative Deamination

11 Amino Acid Oxidase

12 Transamination (Reactions)

13 Summary

14 Degradative Fates of Glutamate Regeneration of a-Ketoglutarate

15 Glutamate-Aspartate Aminotransferase

16 Glutamate Dehydrogenase (Oxidative Deamination)

17 Formation of Urea

18 Degradative Fates of Glutamate Regeneration of a-Ketoglutarate

19 Urea Cycle

20 Urea Cycle (Introduction)

21 Nitrogen Waste Products

22 Classification of Organisms (Nitrogen Excretion Patterns)
Ammonotelic: ammonia excreting Ureotelic: urea excreting Uricotelic: uric acid excreting

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27 Overall Urea Cycle (Liver)

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31 Glutamate Dehydrogenase (Generation of NH3)

32 Carbamyl Phosphate Synthetase (CPS) (Mitochondrion)

33 Carbamyl Phosphate Synthetase (CPS)
CPSI (Mitochondria) Uses NH3 Urea Cycle CPSII (Cytosol) Uses Glutamine Pyrimidine Biosynthesis

34 Ornithine Transcarbamylase (OTC) (Mitochondrion)

35 Glutamate Dehydrogenase

36 Regeneration of Aspartate (Cytosol)

37 Oxidation of 2 NADH Yields 6 ATP

38 Activator

39 Products of Amino Acid Breakdown
Glucogenic Pyruvate – a-Ketoglutarate Succinyl-CoA Fumarate Oxaloacetate Ketogenic Acetyl-CoA Acetoacetate

40 Degradation of amino acids to one of seven common metabolic intermediates.
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41 Animals cannot carryout net synthesis of precursors of gluconeogenesis from acetyl-CoA or acetoacetate

42 Conversion of Pyruvate and Oxaloacetate to PEP (Gluconeogenesis)

43 Degradation to Pyruvate
Alanine, Cysteine, Glycine, Serine and Threonine

44 Degradation of amino acids
Amino acid breakdown can yield: Acetyl-CoA -a-KG Succinyl-CoA OAA fumarate

45 a-KG is generated from five amino acids
Proline Glutamate Glutamine Arginine Histidine

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47 Four amino acids are converted to Succinyl-CoA
Methionine Converted to homocysteine through methyl group transfer, generates cysteine as converted to a-ketobutyrate Isoleucine Transamination, oxidative decarboxylation to acetyl-CoA and propionyl CoA Valine Transamination, decarboxylation to propionyl CoA Threonine - a-ketobutyrate generated and converted to propionyl CoA

48 Propionyl-CoA is a common intermediate for amino acids  succinyl-CoA

49 Branched-chain a-keto acid dehydrogenase complex
In certain body tissues, this enzyme catalyzes the oxidative decarboxylation of valine, isoleucine, and leucine yielding CO2, and acyl-CoA derivatives. Shares ancestry with pyruvate dehydrogenase complex, a-KG dehydrogenase complex – another example of gene duplication

50 Branched-chain …complex

51 Asparagine and aspartate are degraded to OAA

52 Fate of metabolites derived from amino acids
In addition to feeding the citric acid cycle, amino acids can result in ketone bodies, while others are gluconeogenic

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54 Ketone bodies The six amino acids that are degraded to acetoacetyl-CoA and/or acetyl-CoA) can be converted to acetoacetate and b-hydroxybutyrate

55 Glucogenic amino acids
Amino acids that are degraded to pyruvate, a-KG, succinyl-CoA fumarate, and/or OAA can be converted to glucose

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