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Amino acids

N 2 NH 3 or NO 3 -. nitrogenase. soil bacteria. Plants & microorganisms. Amino acids. Plants require Nitrogen in the form of ammonia or nitrate. Animals require nitrogen in the form of amino acids. Both are dependent on soil bacteria to convert atmospheric nitrogen into useable forms.

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Amino acids

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  1. N2 NH3 or NO3- nitrogenase soil bacteria Plants & microorganisms Amino acids Plants require Nitrogen in the form of ammonia or nitrate. Animals require nitrogen in the form of amino acids. Both are dependent on soil bacteria to convert atmospheric nitrogen into useable forms.

  2. Legumes, e.g. soy beans can fix N2 – Grains e.g. wheat/corn cannot – crop rotation Nitrogen-Fixing Nodules

  3. catabolic Oxidative deamination anabolic 3 1 ATP Protein translation N2 NH3 or NO3- RDI for protein 60g Essential aa balance nitrogenase Plants & microorganisms Amino acids 2 transamination Glucose N - Cpds Fat

  4. -keto acids -amino acids Pyruvate Alanine Oxaloacetate COO- | C=O | CH2 | COO- COO- | C=O | R COO- | C-NH2 | R COO- | C=O | CH3 COO- | C-NH2 | CH3 COO- | C-NH2 | CH2 | COO- Aspartic Acid

  5. Glutamic acid COO- | C-NH2 | CH2 | CH2 | COO- Protein Amino Acids Glucose Pyruvate AcetylCoA Aspartic acid NADH/FADH2 COO- | C-NH2 | CH2 | COO- C6 oxaloacetate C4 Krebs Cycle a-ketoglutarate C4

  6. Transamination NH2 | + HOOC - CH - R O || HOOC - C - R O || + HOOC - C - R NH2 | HOOC - CH - R

  7. Amino Transferases transamination enzymes or transaminases amino acid ‘X’ + a-keto acid ‘Y’ ↔ amino acid ‘Y’ + a-keto acid ‘X’ a-ketoglutarateGluand … Aspartate Aminotransferase Asp ↔ oxaloacetate Alanine Aminotransferase Ala↔ pyruvate Tyrosine Aminotransferase Tyr ↔ 4-hydroxyphenylpyruvate Branched Chain AA Aminotransferase (Leu, Ile, Val) PhosphoserineAminotransferase If the a-keto acid corresponding to an amino acid is an intermediate of carbohydrate metabolism then that amino acid may be synthesized via a transamination reaction. Notable examples include Ala (pyruvate), Asp (oxaloacetate), and Glu (a-keto-glutarate).

  8. Alanine Aminotransferase Ala + a-ketoglutarate↔ pyruvate + Glu O || HOOC - C – CH2-CH2-COOH NH2 | + HOOC - CH – CH3 O || + HOOC - C - CH3 NH2 | HOOC - CH - CH2-CH2-COOH

  9. Oxidative Deamination NH2 | HOOC - CH - CH2 - CH2 - COO- + NAD+ + H2O O || HOOC - C - CH2 - CH2 - COO- + NADH + NH4+ Glutamate Dehydrogenase

  10. Oxidative Deamination Transamination Glutamate +a - Keto Acid “X” Glutamate Dehydrogenase  - Ketoglutarate +NH4+ + NADH Amino Acid “X” + a - Ketoglutarate (+ NAD+)

  11. Protein Amino Acids Oxidative Deamination Glucose Glucogenic Amino Acids Glucogenic Amino Acids Will be deaminated via pyruvate or a Krebs intermediate & thus can be converted into glucose. Pyruvate Glucogenic Amino Acids AcetylCoA NADH/FADH2 C6 Ketogenic Amino Acid oxaloacetate C4 Will be deaminated via AcetylCoA and thus can be made into a ketone body. Krebs Cycle a-ketoglutarate C4

  12. Glucogenic/Ketogenic/both ALA CYS GLY SER THR TRP LYS PHE→TYR Glucose ILE LEU TRP Pyruvate ASN ASP PHE TYR ILE MET THR VAL AcetylCoA↔ acetoacetylCoA NADH/FADH2 C6 ARG GLU GLN HIS PRO oxaloacetate C4 Krebs Cycle fumarate SuccinylCoA a-ketoglutarate C4

  13. NH3+ | - CH2 - CH - COO- NH3+ | - CH2 - CH - COO- O || - CH2 - C - COO- PHE Homogentisate Phe Hydroxylase TYR HO - HO - Tyr aminotransferase HO - - OH CH2 - COO-

  14. Homogentisate -OOC - CH = CH - C - CH2 - C - CH2 - COO- || || O O cis trans -OOC - CH = CH - C - CH2 - C - CH2 - COO- || || O O fumarate O acetoacetate H || -OOC - C = C - COO- + H3C - C - CH2 - COO- H HO - - OH CH2 - COO-

  15. Phenylalanine Hydroxylase & PKU Phe + tetrahydrobiopterin Tyr + H2O + dihydrobiopterin [Phe] = 0.1 mM normally  1.2 mM in PKU IQ study: 53  93 1 in 20,000 homozygous 1 in 150 heterozygous

  16. PHE phenylalanine hydroxylase TYR phenylpyruvate Glucose PKU X Pyruvate PKU X Bridging Reaction AcetylCoA↔ acetoacetylCoA NADH/FADH2 C6 oxaloacetate C4 Krebs Cycle fumarate SuccinylCoA a-ketoglutarate C4

  17. OO |||| H3N+- CH - C -N - CH - C - O-CH3 || CH2CH2 | | COO- H aspartame Asp Phe

  18. Protein Amino Acids Ubiquitin Protein digestion (t1/2) Glucose Pyruvate AcetylCoA NADH/FADH2 NAD+/FAD C6 oxaloacetate C4 Krebs Cycle ADP O2 C5 C4 ATP

  19. Ubiquitin is a protein ‘tag’ that marks another protein for proteolytic destruction

  20. Ubiquitin Ubiquitin activating enzyme (E1): ubiquitin + ATP  ubiquitin-AMP + PPi Ubiquitin-conjugating enzyme (E2): attaches to activated ubiquitin via SH Ubiquitin-protein ligase (E3): transfers ubiquitin to e-amino of target protein t1/2 & N-terminal rule (e.g. R = 2 min. M = 20 hrs.) Proteosome: (a 26s protease complex) digests ubiquitin-tagged proteins Slow (>20 hr.) : Ala, Cys, Gly, Met, Pro, Ser, Thr, Val Fast (2-20 min.) : Arg, Asx, Glx, His, Ile, Leu, Lys, Phe, Trp, Tyr Processes regulated by protein destruction gene transcription circadian rhythms inflammatory response antigen processesing tumor supression

  21. Ubiquitin activating enzyme (E1): ubiquitin + ATP  ubiquitin-AMP + PPi Ubiquitin-conjugating enzyme (E2): attaches to activated ubiquitin via SH Ubiquitin-protein ligase (E3): transfers ubiquitin to e-amino of target protein t1/2 & N-terminal rule (e.g. R = 2 min. M = 20 hrs.)

  22. || H2N – C – NH2 O Urea Cycle NH4+ + CO2 + 3ATP + Asp + 2 H2O  urea + 2ADP, Pi + AMP, PPi + fumarate Detoxification of ammonia

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