(c) What is the name of the enzyme that catalyzes the condensation of acetyl-CoA
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(c) What is the name of the enzyme that catalyzes the condensation of acetyl-CoA with oxaloacetate and name two allosteric regulators of this enzyme? 18. The human disease beriberi is caused by a deficiency of thiamine in the diet. People with severe beriberi have higher than normal levels of pyruvate in their blood and urine. Explain this observation in terms of specific enzymatic reaction(s) 18. A recently discovered bacterium carries out ATP synthesis coupled to the flow of electrons through a chain of carriers to some electron acceptor. The components of its electron transfer chain differ from those found in mitochondria; they are listed below with their standard reduction potentials. Electron carriers in the newly discovered bacterium: Electrons transferred E° Oxidant Reductant NAD flavoprotein b (FPb) NADH flavoprotein b -0.32 -0.62 (oxidized) (reduced) cytochrome c (Fe ) Fe-S protein cytochrome c (Fe) +0.22 +0.89 Fe-S protein (reduced) flavoprotein a (reduced) (oxidized) flavoprotein a (FPa) +0.77 (oxidized) Place numbers by the electron carriers in the order in which they are most likely to act in carrying electrons (use 1-5, where 5 is the final electron acceptor). 19. Indicate whether high concentrations of the molecules listed activate (T), inhibit (V) or have no effect (-) on the activity of the indicated enzymes Liver glycogen phosphorylase Muscle glycogen phosphorylase glucagon glucose-6-phosphate NADH epinephrine AMP glucagon Citrate Isocitrate Citric acic Malate cycle o lutarate Fumarate Succinyl-CoAExplanation / Answer
c. Citrate syntase is the enzyme which catalyzes the condensation reaction of Acetyl CoA with oxaloacetate.
oxaloacetate is a 4-carbon substrate, and acetylCoA is a 2-carbon substrate. Citrate synthase catalyzes the condensation to produce Citrate(6-carbon). H2O is required for the reaction.
(1) ATP is an negative allosteric regulator of citrate synthase. ATP increases the Km for acetyl-CoA which reduces the affinity towards AcetylCoA.
(2) SuccinylCoA also is a allosteric inhibitor of this enzyme. SuccinylCoA also reduces the affinity of the enzyme towards AcetylCoA.
18. Thiamine is required for the synthesis of the Cofactor thiamine pyrophosphate (TPP). TPP is required for the catalytic activity of the enzyme pyruvate dehydrogenase, which is a part of pyruvate dehydrogenase enzyme complex. pyruvate dehydrogenase enzyme complex converts pyruvate to acetylCoA and CO2. without thiamine TPP cannot ne formed so, pyruvate produced by glycolysis accumulates in blood and urine.
18.
reducing agents have negative standard reduction potential, so they tend to give electrons to a species which has more positive standard electron potential.
now here we have a list of standard electron potential.
electron pathway
Flavoprotein b reduced (1) to NAD+ (2) to cytochrome c (3) to FPb (4) to FeS (5). FeS is final electron acceptor.
19.
glucagon activates liver glycogen phosphorylase.
higher NADH concentration inhibits liver glycogen phosphorylase
glucose 6 phosphate elivates the activation of liver glycogen phosphorylase
AMP is a activator of muscle glycogen phosphorylase
epinephrine and glucagon both are activators of muscle glycogen phosphorylase
E'0 carrier -0.62 1 -0.32 2 +0.22 3 +0.77 4 +0.89 5Related Questions
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