The malate synthase reaction, which produces malate from acetyl-CoA and glyoxylate in the glyoxylate pathway, involves chemistry similar to the citrate synthase reaction. Write a mechanism for the malate synthase reaction and explain the role of CoA in this reaction.
The malate synthase reaction, which produces malate from acetyl-CoA and glyoxylate in the glyoxylate pathway, involves...
Acetyl COA + H2O Coo- o coo- Citrate synthase CH2 -OH -ooc— CH2 CH2 NADH + H+ COO- Oxaloacetate Coo- Citrate Aconitase Malate dehydrogenase NAD+ - Çoo- Çoo- ---OH -O00—-H HO-CH CH2 CH2 Coo- Malate Coo- Isocitrate Isocitrate lyase Malate synthase COO- COO- Coh CH2 Acetyl COA + H2O Ho Glyoxylate coo Succinate Figure 17.23 Biochemistry, Seventh Edition 2012 W. H. Freeman and Company Question 1 (10 pts) Using diagrams show the pathway that is used to convert succinate to...
3. (10 pts) Citrate synthase catalyzes the reaction: Oxaloacetate + acetyl – COA → citrate + HS – COA The standard free energy change for the reation is -31.5 k] . mol-1. a) Calculate the equilibrium constant for this reaction at 37°C. b) Would you expect this reaction to serve as a control point for its pathway (the citric acid cycle)?
The reaction catalyzed by malate dehydrogenase, Malate + NAD+ → oxaloacetate + NADH + H+ has a ΔG°′ value of +29.7 kJ · mol−1. (a) Would this reaction occur spontaneously in a cell? (b) How does the citrate synthase reaction (described in Problem 7) promote the malate dehydrogenase reac- tion in the cell? What is the overall change in free energy for the two reactions? 7. Citrate synthase catalyzes the reaction Oxaloacetate + acetyl-CoA → citrate + HS-CoA The standard...
not sure about reaction 3 and 4
acetyl-CoA COA The reactions of the citric acid cycle are shown in the figure Reactions 1, 3, and 4 are regulation points in the citric acid cycle. 1 citrate oxaloacetate 1 synthase citrate NADH + NAD malate dehydrogenase aconitase 2 malate Which of the molecules inhibits reaction 1? Isocitrate HO 17 fumarase NAD socitrate 3 dehydrogenase S D NADP ADP ОАТР O citrate synthase fumarate FADHI succinate co-ketoglutarate dehydrogenase ci-ketoglutarate NAD dehydrogenase +...
acetyl-CoA COA The reactions of the citric acid cycle are shown in the image. As labeled in the diagram, reactions 1, 3, and 4 are regulation points in the citric acid cycle. oxaloacetate citrate synthase citrate NADH +Hi 7 malate dehydrogenase NAD malate aconitase 2 Which molecule inhibits reaction 1? isocitrate 7 fumarase NAD isocitrate dehydrogenase 3 NADH + H+ O citrate O NAD acetyl-CoA + CO2 fumarate C-ketoglutarate FADH succinate O dehydrogenase FAD O-ketoglutarate a dehydrogenase NAD + COA...
Choose the ONE BEST answer explaining how oxaloacetate and acetyl-CoA levels are balanced to maximize flux through the citrate cycle when energy charge in the cell is lovw Oxaloacetate is required for mitochondrial shuttle systems, and therefore it makes sense to activate pyruvate carboxylase by ATP and inhibit it by malate. None of the answers are correct. The best way to balance the input of carbon into the citrate cycle is to regulate the production of citrate using vitamins like...
Succinyl-CoA is a negative regulator of citrate synthase. Explain why this makes sense, and propose a possible mechanism for how this molecule inhibits citrate synthase. What other step of the citric acid cycle is inhibited by succinyl-CoA, and how do you expect that inhibition mechanism to be similar/different?
Describe “hub” molecules acetyl CoA and pyruvate that serve
different pathways. Explain metabolic regulation favoring metabolic
pathway choices leading to and from hub molecules. Describe how
C.A.C. serves as a “hub “pathway. Use picture as a reference.
Pyruvate Glucose Fatty acids sterols pyruvate carboxylase Acetyl-CoA PEP carboxykinase Glutamine Citrate Phosphoenolpyruvate (PEP) Proline Arginine Oxaloacetate PEP carboxylase Citric acid cycle a-Ketoglutarate Malate Glutamate Aspartate Asparagine Serine Glycine Cysteine malic enzyme Purines Succinyl-CoA Phenylalanine Pyrimidines Pyruvate Tyrosine Tryptophan Porphyrins heme Figure 16-16...
Cholesterol biosynthesis involves a stepwise increase of carbon numbers from acetyl-CoA (C2) to ______ (C5), and, finally, to squalene (C30). But, the rate-limiting step is catalyzed by _____. Inhibition of this enzyme is adopted as a strategy for the therapeutic control of cholesterol levels. Select one: a. isoprenoid ;;; HMG CoA synthase b. isoprenoid ;;; HMG CoA reductase c. flavonoid ;;; HMG CoA synthase d. flavonoid ;;; HMG CoA reductase e. None of these
Which enzymes require thiamine as a co-factor A. Isocitrate dehydrogenase and citrate synthase B. Malate dehydrogenase and alpha-ketoglutarate dehydrogenase C. Pyruvate dehydrogenase and isocitrate dehydrogenase D. Pyruvate dehydrogenase and succinyl-CoA synthetase E. Succinate dehydrogenase and pyruvate dehydrogenase