Amino Acid Metabolism

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  1. What does it mean to be Ammonotelic?
    • Excrete ammonia (which would poison us if floating around in our bodies)
    • Fish
  2. What does it mean to be Uricotelic?
    • Excrete uric acid (guano)
    • Birds
  3. What does it mena to be Ureotelic?
    • Excrete non-toxic, water-soluble urea
    • Land animals, US!
  4. Nitrogen Balance
    Nitrogen intake matches nitrogen excreted
  5. Positive Nitrogen Balance
    • Excess Nitrogen ingested over excreted
    • eg. Pregnancy and Growth
  6. Negative Nitrogen Balance
    • Nitrogen output exceeds intake
    • eg. Surgery, cancer, Kwashiorkor, Marasmus
  7. How much total protein is turned over daily?
    • 1-2% of total body protein/day turnover
    • -2 other fun facts
    • 75% of the liberated amino acids are reutilized
    • 25% nitrogen converted to urea and carbon skeleton converted to metabolic intermediates
  8. What can produce urea?
  9. Glucose-Alanine Cycle
    Glucose converted to Alanine to enter blood stream and then liver, Alanine convereted to glutamate, NH4+, and urea or Glucose to then be excreted into the blood stream.
  10. What are the steps involved in Nitrogen catabolism?
    • 1. Transamination (remove amino group)
    • 2. Oxidatibe deamination of glutamate
    • 3. Ammonia transport (to liver)
    • 4. Reactions to the urea cycle (5 enzymes involved)
  11. Aminotransferases catalyze transamination
    amino acid + keto acid <--(aminotransferase)--> keto acid + amino acid
  12. Alanine come from...?
    Serine comes from...?
    What organ are they going to and what is excreted?
    • Alanine- Muscle, gut, kidney
    • Serine- kidney
    • Liver --->Urea, glucose
  13. Aspartate + alpha-ketoglutarate (amino group) <---->Oxaloacetate + glutamate converted by what enzyme?
    • Aspartate Aminotransferase (AST)
    • SGOT
  14. Alanine + alpha-ketoglutartate <---> pyruvate + glutamate converted by which enzymes?
    • Alanine Aminotransferase (ALT) --->
    • (SGPT) <--
  15. Glutamate Dehydrogenase, a rate limiting enzyme in amino acid catbalism is inhibited by what?
    • High energy
  16. Glutamate Dehydrogenase, a rate limiting enzyme in amino acid catabolism is stimulated by what?
    ADP, GDP
  17. Serine--Serine Dehyratase--> Leads to?
    Pyruvate and NH4+
  18. Threonine --Threonine Dehyratase--> Leads to?
    alpha-ketobutyrate and NH4+
  19. Ammonia is converted to?
    Where are the carbons and nitrogens from?
    • Urea
    • Carbon from CO2
    • 1 Nitrogen from Aspartate
    • 1 Nitrogen from Ammonia
  20. Where does urea cycle occur?
    Parts in mitochondria and parts in cytoplasm of Liver cells
  21. What are the amino acids is the urea cycle?
    • Ornithine
    • Citrulline
    • Arginine
  22. What does Aspartate become in urea cycle?
  23. What is fumarate converted to?
    • Glucose
    • Aspartate
  24. Hyperammonenemia Type I
    • CPSynthetase I deficiency
    • 1st emzyme toxic, serious condition
  25. Hyperornithinemia, hyperammonemia, and homocitrullinuria syndrome (HHH Syndrome)
    Ornithine transporter defect
  26. Hyperammonemia Type II
    • Ornithine Transcarbamoylase deficiency
    • X-linked disease
  27. Citrullinemia
    Argininosucinate synthetase deficiency
  28. Argininosuccinicaciduria
    Argininosuccinase or argininosuccinate lyase deficiency
  29. Hyperargininemia
    Arginase deficiency
  30. What amino acids are purely ketogenic?
    • Leucine
    • Lysine
  31. What amino acids are ketogenic and glucogenic?
    • Phenylalanine
    • Tryptophan
    • Tyrosine
    • Isoleucine
  32. What enzymes are purely glucogenic?
    • Alanine
    • Cysteine
    • Glycine
    • Serine
    • Asparagine
    • Aspartate
    • Methionine
    • Threonine
    • Valine
    • Arginine
    • Glutamate
    • Glutamine
    • Histidine
    • Proline
  33. Phenylalanine + O2 + tetrahydrobiopropterin (cofactor) oxidized by what? To What?
    --Phenylalanine hydroxylase--> Tyrosine + H2O + quinonoid dihydrobiopterin
  34. Methionine is degraded into what?
    Succinyl CoA
  35. Citrullinema
    • Argininosuccinase deficiency
    • Lethargy, seizures, reduced muscle tension
  36. Tyrosinemia
    • Various enzymes of tyrosine degradation deficiency
    • Weakness, self-mutilation. liver damage, mental retardation
  37. Albinism
    • Tyrosinase deficiency
    • Absence of pigmentation
  38. Homocystinuria
    • Cystathionine Beta-synthase deficiency
    • Scoliosis, muscle weakness, mental retardation, thin blonde hair
  39. Hyperlysinemia
    • alpha-Aminoadipic semialdehyde dehydrogenase deficiency
    • Seizures, mental retardation, lack of muscle tone, ataxia
  40. Histidinemia
    Histidase deficiency
  41. Glycinuria
    Defect in reanl tubular reabsorption
  42. Cystine-lysinuria
    Defect in renal tubular reabsorption
  43. Cystinosis
    Cystine storage disease
  44. Alkaptonuria
    hoomogentisate oxidase deficiency
  45. Maple syrup urine disease (branched-chain ketonuria)
    alpha-ketoacid decarboxylase complex defect
  46. Phenylketonuria
    Classic PKU or Type 1
    Types II and III
    Types IV and V
    • Classic PKU or Type 1- Phenylalanine hydroxylase deficiency
    • Types II and III- dihydrobiopterin reductase deficiency
    • Types IV and V- dihydrobiopterin biosynthesis defect cofactor not avaliable
  47. Essential amino acids
    must be obtained from diet
  48. Nonessential amino acids
    can be synthesized
  49. What is the entry point for ammonia?
  50. Glutamate dehydrogenase
    • Mitochondrial enzyme present in mammals mainly used for catabolism
    • NH4+ + alpha-ketoglutarate + NAD(P)H + H+ --Glutamate dehydrogenase--> Glutamate + NAD(P)+ + H2O
  51. Glutamine Synthetase
    Adds NH4+ to Glutamate to convert it to Clutamine
  52. Glutamate Synthase
    • No present in animals predominantly in plants
    • 2 Glutamate generated from alpha-ketoglutarate and gluamine with the addition of NADPH
  53. Transaminase
    • Amino transerase
    • ALT
    • AST
  54. Glutamate (AA) + Pyruvate (alpha-keto acid) <----> Alpha-ketoglutarate (alpha-keto acid) + Alanine (Amino acid)
    What enzyme?
    ALT a transaminase
  55. Glutamate (AA) + Oxaloacetate (alpha-keto acid) <----> Alpha-ketoglutarate (alpha-keto acid) + Aspartate (Amino acid)
    What enzyme?
    AST a transaminase
  56. What does Transamination require?
    Vitamin B6
  57. Histidine comes from?
    • Ribose 5-Phosphate
    • Purely from PPP
  58. Serine comes from?
    And leads to?
    • 3-Phosphoglycerate
    • Leads to Cysteine and Glycine
  59. Cysteine and Glycine come from?
    Serine which comes from 3-Phosphoglycerate
  60. Phenylalanine and Tryptophan come from?
    What do they lead to?
    • Phosphoenolpyruvate and Erthrose 4-phosphate
    • Tyrosine
  61. Aspartate comes from?
    And leads to?
    • Oxaloacetate
    • Asparagine, Methionine, Threonine. Lysine
  62. Alainine, Valine, and Leucine come from?
  63. Glutamate comes from?
    Leads to?
    • alpha-ketoglurarate
    • Glutamine, Proline, Arginine
  64. Glutamine, proline, arginine come from?
  65. Vitamin B9 is required for?
    Tetrahydrogolate formation which is needed during amino acid synthesis
  66. One carbon groups carried by tetrahydrofolate?
    • -CH3 Methyl
    • -CH2- Methylene
    • -CHO Formyl
    • -CHNH Formimino
    • -CH-- Methenyl
  67. Methanol
    most reduced
  68. Formaldehyde
    Intermediate oxidation state
  69. Formic acid
    Most oxidized
  70. Cysteine can be synthesized from?
    • Methionine
    • Requires SAM (ethyl donor group)
  71. Feed back inhibition can be?
    Linear and branched
  72. Isoleucine _______ Threonine deaminase and Valine ______ it
    • Inhibits
    • Activates
  73. Aspartokinase can be inhibited by what?
    • Threonine
    • Lysine
Card Set
Amino Acid Metabolism
BioChem Amino Acid Metabolism
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