10.4-10.5 Regulation of the citrate cycle Flashcards
how is pyruvate dehydrogenase regulated? (generally)
by energy charge
how is pyruvate dehydrogenase inhibited?
when energy charge is high, pyruvate dehydrogenase kinase phosphorylates serine on E1
how is pyruvate dehydrogenase activated?
when energy charge is low, phosphatase removes that phosphate from serine on E1
what 3 molecules inhibit pyruvate dehydrogenase?
- NADH
- acetyl-CoA
- ATP
what 4 molecules activate pyruvate dehydrogenase?
- NAD+
- CoA
- ADP
- also Ca2+
what 3 reactions are irreversible in the citrate cycle?
1, 3, 4
describe the general porcess of citrate cycle inhibition
products generally inhibit the enzymes that created them by feedback inhibition
describe the general process of citrate cycle activation
activators are generally on the reactant side, driving the reactions forward
how is citrate synthase activated (1)? inhibited (4)?
activated: by ADP
inhibited: NADH, citrate, ATP, succinyl-CoA
how is isocitrate dehydrogenase activated (2)? inhibited? (2)
activated: ADP and Ca2+
inhibited: NADH, ATP
how is alpha-ketogluterate dehydrogenase activated (2)? inhibited (3)?
activated: AMP, Ca2+
inhibited: NADH, succinyl-CoA, ATP
how is pyruvate decarboxylase activated?
Acetyl-CoA
how is citric acid uses commercially? where is it obtained from?
used as a commercial food preservative, obtained from lemons
how was citrate production maximized experimentally?
used culture conditions that inhibit citrate lyase and reactions 2-8 of the citrate cycle, yielding a mold strain with a high capacity for citrate export
how does the citrate cycle generate redox energy? what does this redox energy do?
generates redox energy by oxidizing acetyl-CoA which reduces NAD+ and FAD
