Day 38

Question 1

Regulation of Pyruvate Dehydrogenase

Answer 1

1) Product Inhibition
- NADH and acetyl CoA compete with NAD+ and CoA for enzyme’s binding sites. “well fed” turn off
2) Covalent Modification
- NADH and acetylCoA activate pyrucate dehydrogenase kinase which will phosphorylate the E1 complex and inactive it
- Insulin will reverse it by activating pyruvate dehydrogenase

Question 2

CAC Rate Controlling Steps

Answer 2

Steps 1, 3, 4

• CAC is inactivated by NADH, ATP
• CAC is activated by Ca2+, ADP (calcium signals both muscle contraction and energy production)

Question 3

CAC Regulation

Answer 3

• Not allosteric but it regulated by substrate availability, product inhibition, competitive feedback inhibition
• mvp regulators; acetyl-CoA, oxaloacetate, NADH
• acetyl-CoA and oxaloacetate are not present in concentration in the mitochondira to saturate citrate synthase so substrate concentration really important
• ATP and ADP are allosteric effectors
• Ca2+ can activate pyruvate dehydrogenase phosphatase and isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase.