(c) (1) Fluoroacetate, prepared commercially for rodent control, is also produced by a South Afri-can plant. After entering a cell, fluoroacetate is converted to fluoroacetyl-CoA in a reaction catalyzedby the enzyme acetate thiokinase:F-CH2COO¯ + COA-SH + ATPF-CH2CO-SCOA + AMP + PPjThe toxic effect of fluoroacetate was studied in an experiment using intact isolated rat heart. After theheart was perfused with 0.22 mM fluoroacetate, the measured rate of glucose uptake and glycolysisdecreased, and glucose 6-phosphate and fructose 6-phosphate accumulated. Examination of the cit-ric acid cycle intermediates revealed that their concentrations were below normal, except for citrate,with a concentration 10-fold higher than normal.Where did the block in the citric acid cycle occur? What caused citrate to accumulate and the othercycle intermediates to be depleted? Explain. Why does it block the citric acid cycle?Fluoroacetyl-CoA is enzymatically transformed in the citric acid cycle. Name and draw the structure ofthe end product of fluoroacetate metabolism?How might the inhibition be overcome? Explain.

Let's go ahead and go further into each individual facet, shall we?1. Interrupt the citric acid…

Answered: (c) (1 ) Fluoroacetate, prepared…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter19: The Tricarboxylic Acid Cycle

Section: Chapter Questions

Problem 22P: Study Figure 19.18 and decide which of the following statements is false. Pyruvate dehydrogenase is...

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Study Figure 19.18 and decide which of the following statements is false. Pyruvate dehydrogenase is inhibited byÂ· NIADH. Pyruvate dehydrogenase is inhibited by AÎ¤Î¡. Citrate synthase is inhibited by NADH. Succinyl-CoA activates citrate synthase. Acetyl-CoA activates pyruvate carboxylase.
In the first step of the TCA cycle the acetyl group of acetyl-CoA is transferred to oxaloacetate to produce citrate. Where will the carbonyl carbon of that acetyl group be after the first CO2 is expelled? Group of answer choices The first carbon of α-ketoglutarate The last carbon of α-ketoglutarate The fourth carbon of α-ketoglutarate The third carbon of α-ketoglutarate
Complete the following paragraph describing the fate of the second 14CO-acetyl-CoA molecule incorporated into the glyoxylate cycle. The glyoxylate produced in the isocitrate reaction combines with a (A.) 2nd molecule of oxoaloacetate, B.) 2nd molecule of succinate, C.)2nd molecule of acetyl coa) in the malate synthase reaction. Malate is (A.Chiral, B.diasteromeoic C.)Achiral) ; therefore, the oxaloacetate produced from glyoxylate will be labeled at (A.Either of carboxylate carbon B. specifically at methylene carbon C. Specifically at carbonyl carbon D. Specifically at carboxylate carbon bonded to methylene).
One consequence of ethanol addiction is fatty liver disease, an illness in which liver cells accumulate large amounts of triacylglycerols, the esters derived from glycerol and fatty acids. Ethanol is oxidized in the cytoplasm of liver cells by alcohol dehydrogenase and aldehyde dehydrogenase to yield acetate and 2 NADH. Acetate is then transported into the mitochondrion, where it is converted to acetyl-CoA and metabolized in the citric acid cycle. When alcohol is consumed in excessive quantities, the resulting high levels of NADH cause metabolic abnormalities, one of which is high levels of fatty acid synthesis. Fatty acid synthesis, also a cytoplasmic process, uses acetyl-CoA as a substrate and NADPH as a reducing agent. Speculate about how a high level of cytoplasmic NADH provides a source of NADPH for fatty acid synthesis.
succinyl-COA synthetase will do which of the following: Select one: a. Fumarate is combined with water to become Malate b. alpha-ketoglutarate is oxidized and decarboxylated to produce Succinyl-CoA, Carbon dioxide and NADH c. Succinate is oxidized to become fumarate forming FADH2 d. Citrate is rearranged to become Isocitrate e. Malate is oxidized to become oxaloacetate forming NADH f. Pyruvate is decarboxylated to become acetyl-CoA producing NADH and Carbon dioxide g. Succinyl-CoA becomes Succinate and forms one ATP molecule and Coenzyme A-SH h. Oxaloacetate combines with the acetyl from acetyl-CoA to produce Citric acid(citrate) i. Isocitrate and then decarboxylated and oxidized to produce alpha-ketoglutarate, Carbon dioxide and NADH
Which of the following statements is falseconcerning acetyl CoA carboxylase (ACC)? ACC is more active when protomers condense to form polymers Palmitoyl CoA serves as a feedback inhibitor The source of carbons for ACC comes from the carbon skeletons of malate that is exported from the matrix of the mitochondria in the form of malate Binding of glucagon triggers cAMP production, which leads to inhibition of ACC
Synthesis of the activated form of acetate (acetyl-CoA) is carried out in an ATP-dependent process:(a) The ΔG′° for hydrolysis of acetyl-CoA to acetate and CoA is −32.2 kJ/mol and that for hydrolysis of ATP to AMP and PPi is −30.5 kJ/mol. Calculate ΔG′° for the ATPdependent synthesis of acetyl-CoA.(b) Almost all cells contain the enzyme inorganic pyrophosphatase, which catalyzes the hydrolysis of PPi to Pi. What effect does the presence of this enzyme have on the synthesis of acetyl-CoA? Explain.
In the presence of saturating amounts of oxaloacetate, the activity of citrate synthase from pig heart tissue shows a sigmoid dependence on the concentration of acetyl‑CoA. When succinyl‑CoA is added, the curve shifts to the right and the sigmoid dependence is more pronounced.
The malaria parasite Plasmodium falciparum does not carry out oxidative phosphorylation and therefore does not use the citric acid cycle to generate reduced cofactors. Instead, the parasite converts amino acid–derived α ketoglutarate to succinate. Write an equation for the α-ketoglutarate → succinate conversion that follows (a) the oxidative (clockwise) path of the citric acid cycle or (b) the reductive (counterclockwise) path of the cycle.
Acetly CoA can quickly enter the citric acid cyle by joining with a C4 compound and forming citrate. Meanwhile, GTP (or ATP) is generated using inorganic phosphate while succinyl CoA is converted to succinate. What is the main reason both acetly CoA and succinyl CoA can perform such work? a. Acetyl CoA and succinyl CoA both contain coenzyme A, which is a high-energy compound. b. Acetyl CoA and succinyl CoA both form an unstable thioester bond with coenzyme A. c. Acetyl CoA and succinyl CoA both bind with inorganic phosphate which is used to generate ATP (or GTP). d. Acetyl CoA and succinyl CoA both transiently form a covalent bond with the enzymes that catalyze the next reaction, pyruvate dehydrogenase and succinyl-CoA synthetase, respectively. e. Acetyl CoA and succinyl CoA use the energy collected from the electron transport chain.
For each of the central pathway intermediates given below, calculate how many ATP equivalents can be generated by complete oxidation of the compound to CO2: 1. Acetyl-CoA 2. Pyruvate 3. GAP (glyceraldehyde-3-phosphate) And please explain why.
Which of the following citric acid cycle enzymes catalyzes substrate-level phosphorylation? A) isocitrate dehydrogenase B) α-ketoglutarate dehydrogenase C) succinyl CoA synthetase D) succinate dehydrogenase E) malate dehydrogenase

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