NUTR 600 Enzymes Exam 1

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emmayarewhy
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172813
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NUTR 600 Enzymes Exam 1
Updated:
2012-09-23 23:53:44
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enzymes allosteric activators
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regulatory enzymes and their regulations (1) what, activated by, deactivated by, notes.
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  1. Glycogen phosphorylase (4,4)
    Activated by: glucagon, epinephrine, AMP in muscle, and Ca2+

    Deactivated by insulin, ATP, glucose, G6P
  2. Glycogen synthase (2,2)
    Activated by insulin and G6P


    Deactivated by glucagon, Ca2+ via PKC
  3. Glucokinase (2,1) vs. Hexokinase (1,1)
    • Both responsible for glucose --> G6P
    • Both activated by glucose. 

    Glucokinase: High Vmax, High Km. Activated by insulin and  deactivated by F6P

    Hexokinase: Found in most cells, low Vmax, low Km.  deactivated by G6P.
  4. PFK-1 (4,2)
    F6P--> F1,6BP

    • Activated by F2,6BP (insulin, PFK2), AMP
    • Deactivated by Citrate, ATP
  5. Pyruvate kinase (2,2)
    PEP --> Pyruvate (Glycolysis)

    • Activated by Insulin, F1,6BP
    • Deactivated by Glucagon, Acetyl CoA
  6. PDH (5)
    • Pyruvate --> acetyl CoA
    • 3 enzymes, 5 coenzymes (thiamine pyrophosphate, lipoic acid, NAD+, FAD, CoA) Thiamine, riboflavin, niacin, and pantothenic acid. 

    • Activated by: PDH phosphatase, insulin,
    • Deactivated by: PDH kinase,glucagon, ATP, NADH, acetyl CoA
  7. PDH kinase (3,1)
    Dephosphorylates (deactivates) PDH 

    Activated by NADH, ATP, acetyl CoA

    Inhibited by pyruvate
  8. Citrate synthase (0,4)
    Acetyl CoA + OAA -->Citrate

    Inhibited by ATP, NADH, succinyl CoA, long chain fatty acyl CoA
  9. Isocitrate dehydrogenase (2,2)
    Activated by ADP & Ca2+

    Inhibited by ATP, NADH
  10. A-ketoglutarate dehydrogenase
    Inhibited by ATP, NADH, GTP, succinyl CoA
  11. Summary of TCA cycle rxn:
    2 3C pyruvates --> 2 acetyl CoA + 2 NADH

    2 Acetyl CoA --> 4 CO2, 6 NADH, 2 FADH2, 2 GTP
  12. Summary of glycolysis
    6C --> 2 3C pyruvates + 2 ATP + 2 NADH
  13. Summary of ETC
    10 NADH + 2 FADH2 --> H2O + 34 ATP
  14. What inhibits parts of ETC? 5 parts that can be inhibited
    • NADH dehydrogenase - barbituates
    • Cyt b--> cyt c - antimycin A
    • cytochrome oxidase (a.a3) - CO, H2S, cyanides
    • Uncouplers - make inner mitochondrial membrane more permeable --> aspirin

    ATP synthase: oligomycin
  15. G6P dehydrogenase (1,1)
    Rate limiting enzyme in PPP

    Activated by insulin, inhibited by high levels of NADPH
  16. What regulates GNG? 6
    • 1. Availability of gluconeogeneic substrates
    • 2. Availability of energy (4 ATP, 2 GTP, 3 NADH)
    • 3. Glucagon: activates transcription of G6Ptase, PEPCK, and inhibits pyruvate kinase via PKA via cAMP
    • 4. Acetyl CoA: activates pyruvate carboxylase, deactivates pyruavte kinase. 
    • 5. AMP: deactivates F1,6BPtase,activates PFK-1
    • 6. ATP: activates F1,6BPtase
  17. Pyruvate carboxylase
    pyruvate --> OAA

    Activated by acetyl CoA
  18. PEPCK
    OAA --> PEP

    Activated by glucagon (transcription, like G6Ptase)
  19. F1,6BPtase (2,2)
    F1,6BP --> F6P

    • Activated by ATP, glucagon
    • Inhibited by AMP, F2,6BP
  20. G6Ptase
    Glucose 6 P --> Glucose

    Activated by glucagon (via transcription)

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