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Glycogen phosphorylase (4,4)
Activated by: glucagon, epinephrine, AMP in muscle, and Ca2+
Deactivated by insulin, ATP, glucose, G6P
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Glycogen synthase (2,2)
Activated by insulin and G6P
Deactivated by glucagon, Ca2+ via PKC
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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.
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PFK-1 (4,2)
F6P--> F1,6BP
- Activated by F2,6BP (insulin, PFK2), AMP
- Deactivated by Citrate, ATP
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Pyruvate kinase (2,2)
PEP --> Pyruvate (Glycolysis)
- Activated by Insulin, F1,6BP
- Deactivated by Glucagon, Acetyl CoA
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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
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PDH kinase (3,1)
Dephosphorylates (deactivates) PDH
Activated by NADH, ATP, acetyl CoA
Inhibited by pyruvate
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Citrate synthase (0,4)
Acetyl CoA + OAA -->Citrate
Inhibited by ATP, NADH, succinyl CoA, long chain fatty acyl CoA
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Isocitrate dehydrogenase (2,2)
Activated by ADP & Ca2+
Inhibited by ATP, NADH
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A-ketoglutarate dehydrogenase
Inhibited by ATP, NADH, GTP, succinyl CoA
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Summary of TCA cycle rxn:
2 3C pyruvates --> 2 acetyl CoA + 2 NADH
2 Acetyl CoA --> 4 CO2, 6 NADH, 2 FADH2, 2 GTP
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Summary of glycolysis
6C --> 2 3C pyruvates + 2 ATP + 2 NADH
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Summary of ETC
10 NADH + 2 FADH2 --> H2O + 34 ATP
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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
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G6P dehydrogenase (1,1)
Rate limiting enzyme in PPP
Activated by insulin, inhibited by high levels of NADPH
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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
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Pyruvate carboxylase
pyruvate --> OAA
Activated by acetyl CoA
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PEPCK
OAA --> PEP
Activated by glucagon (transcription, like G6Ptase)
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F1,6BPtase (2,2)
F1,6BP --> F6P
- Activated by ATP, glucagon
- Inhibited by AMP, F2,6BP
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G6Ptase
Glucose 6 P --> Glucose
Activated by glucagon (via transcription)
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