Ch. Gen Q’s Flashcards
(19 cards)
What does the citrate cycle do?
Oxidizes acetyl-CoA into 3 units of NADH, 1 unit of FADH2, and 1 unit of GTP
GTP gets converted into ATP
How does the citrate cycle generate 3 NADH and 1 FADH2?
Transfers 8 electrons from oxidized acetyl CoA to NAD+ and FAD
What are the five co-enzymes involved in the PDH complex?
NAD+, FAD, CoA, TPP, a-lipoic acid (lipoamide)
What are the three main enzyme subunits of the PDH complex?
E1 pyruvate dehydrogenase, E2 dihydrolipoyl acetyl transferase, E3 dihydrolipoyl dehydrogenase
What are the functions of the coenzyme a-lipoic acid?
- Provides a reactive disulfide that can participate in redox reactions within the enzyme active site
- located on the E2 subunit, functions as a bridge between the E1 and E3 subunits
Which coenzyme a transfers the acetyl group to CoA-SH?
TPP
What is the function of arsenite?
Functions as an inhibitor of lipoamides via covalent bonds
What is the function of pyruvate dehydrogenase kinase (PDK)?
Inhibits PDH by inducing serine phosphorylation on the E1 subunit
What is the function of pyruvate dehydrogenase phosphatase?
Acts as an activator of PDH by dephosphorylating the serine residue on E1
What are the two inhibitors of PDK?
NAD+ and ADP
Describe the interactions of the three subunits in the PDH complex (3 bullet points)
- E2 Lipoamide picks up an acetyl group from TPP on E1 subunit
- E2 pivot disassociates from E1 and binds to E3
- E2 ball and Chain delivers acyl group to CoA in E2 catalytic domain
What is the function of FADH & NADH?
Are used to power the electron transport system resulting in the production of 10 ATP for every acetyl CoA that enters the citrate cycle
What are the five coenzymes used by the pyruvate dehydrogenase complex?
NAD+, FAD, CoA, TPP, and a-lipoic acid
A deficiency in this vitamin causes the human disease beriberi
Thiamine
What are the three enzymes used by the pyruvate dehydrogenase complex?
E1 pyruvate dehydrogenase
E2 dihydrolipoyl acetyltransferase
E3 dihydrolipoyl dehydrogenase
What occurs in the pyruvate dehydrogenase five step reaction?
Steps 1, 2, and 3 lead to the formation of acetyl, CoA, and step 4 and 5 regenerate the oxidized form of lipoamide and reduce NAD+ to NADH plus H+
What does citrate synthase do?
Catalyzes the condensation of oxaloacetate and acetyl-CoA to form citrate
What does isocitrate dehydrogenase do?
Catalyzes the decarboxylation of isocitrate by transferring two electrons to NAD+ to form NADH2 plus releases CO2
What does alpha ketoglutarate dehydrogenase do?
Catalyzes in oxidative decarboxylation that produces carbon dioxide, NADH, and succinyl-CoA
