Flashcards in Oxidation of Pyruvate and TCA Cycle Deck (24):
Oxidation of pyruvate and the TCA cycle account for complete oxidation of glucose to what?
CO2 and H2O
Pyruvate formed in the cytosol is transported into the mitochondrion by a ____ ____
Inside the mitochondrion, pyruvate is oxidatively decarboxylated to acetyl-CoA by ____ ____ multienzyme complex
pyruvate dehydrogenase (PDH)
note: 3 enzymes, 5 coenzymes, regulatory proteins
Pyruvate is covalently bound to ___ associated with first enzyme of the pyruvate dehydrogenase
Dihydrolipoyl transacetylase catalyzes the transfer of acetyl group to CoA-SH, which leaves the lipoic acid in the ____, ____ form
The oxidized form of _____ is regenerated by dihydrolipoyl dehydrogenase
Activity of the PDH complex is affected by _____/_____
note: inactive when phosphorylated
Where does the TCA cycle take place in the cell?
matrix of mitochondria
In regards to the TCA cycle, oxidation of acetylCoA produces reduced ____ and ____
In regards to the TCA cycle, deoxidation of NADH and FADH2 through the ____ ____ chain, reduces O2 to H2O
What are other roles of citrate?
source of other synthetic pathways (FAs)
regulation of other reactions (PFK-1)
source of reducing equivalents
The isomerization of citrate to isocetrate by aconitase is ___, with the migration of the -OH from the central carbon of citrate being always adjacent to the carbon which is derived from the -CH2- of OAA
Which enzyme produces the first NADH and CO2 of the TCA cycle
What is the rate limiting step of the TCA cycle?
isocitrate to alpha-ketoglutarate
enzyme: isocitrate DH
alpha-ketoglutarate dehydrogenase has 3 catalytic subunits E1, E2, and E3. Give the requirements of this enzyme, and mention if it is regulated by phosphorylation.
requires: TPP, lipoid acid, CoASH, FAD, NAD+
NOT regulated by phosphorylation
Which enzyme produces the second NADH and CO2 of the TCA cycle?
What is the only substrate level phosphorylation of the TCA cycle?
Succinyl CoA synthetase/succinate thiokinase
Which enzyme of the TCA cycle produces FADH2 (third reducing equivalent
Which enzyme of the TCA cycle produces the fourth (and final) reducing equivalent, NADH?
What determines the rate of the TCA cycle?
rate of ATP utilization
Citrate synthase is inhibited by ____-___
Isocitrate DH is stimulated by ____, inhibited by ____
alpha-ketoglutarate is inhibited by _____-___, ___ and ____
succinyl-CoA; NADH; GTP