10.3 Citrate Cycle enzymatic reactions

what happens if o2 is limited during the citrate cycle

NADH and FADH2 accumulate and citrate cycle is feedback inhibited

what are the enzymes for the three highly favorable reactions in the citrate cycle

citrate synthase, isocitrate dehydrogenase, and alpha ketoglutarate dehydrogenase

which enzymes are the key regulators for the citrate cycle and why

citrate synthase, isocitrate dehydrogenase, and alpha ketoglutarate dehydrogenase; highly favorable reactions are essentially irreversible

what has 14C labeled carbons shown about the citrate cycle

how important it is to regenerate metabolic intermediates in a cyclic pathway to maintain flux

what does citrate synthase do

takes acetyl-CoA and oxaloacetate to make citrate through a condensation reaction; large conformational change

what happens in isomerization of citrate to form isocitrate

Fe-S cluster removes Oh frmo citrate

what is fluoroacetate

a toxic compound converted to fluorocitrate which blocks citrate export from mitochondria

what is the rate limiting step of the citrate cycle

isocitrate dehydrogenase reaction

what is the substrate for the first reaction of the citrate cycle

oxaloacetate (the end product of the citrate cycle)

what three factors regulate the citrate cycle

substrate availability, product inhibition, and feedback control of key enzymes

what three enzymes regulate the citrate cycle

isocitrate dehydrogenase, alpha ketoglutarate dehydrogenase, isocitrate dehydrogenase

what inhibits citrate synthase, isocitrate dehydrogenase, and alpha ketoglutarate

high NADH to NAD+ ratios; ATP; succinyl CoA

what activates enzymes in the citrate cycle

ADP; Ca2+

why does it make sense that Ca2+ stimulates pyruvate dehydrogenase activity

continual ATP is needed during muscle contraction

what are two types of feedback inhibition in the citrate cycle

product inhibition (citrate synthase and NADH) and metabolite inhibition (ATP)

is the citrate cycle anabolic or catabolic

amphibolic because it both oxidizes acetyl CoA and anabolically produces precursors for fatty acid, amino acid, and heme synthesis

what are anaplerotic reactions

reactions that replenish citrate cycle intermediates that have been shunted to other metabolic pathways

which citrate intermediates are precursors for other pathways

citrate, alpha ketoglutarate, succinyl coa, malate, and oxaloacetate

what does the enzyme pyruvate carboxylase do

balances input of acetyl coA in the citrate cycle by making a way to convert pyruvate into oxaloacetate using ATP carboxylation