he immediate precursor to acetyl–CoA from glycolysis is pyruvate. a) Write the pathway (not the mechanism) for the series of steps for this conversion. Include structures for all coenzymes and reactants for each step. b) Discuss the mechanistic advantages offered by this multienzyme complex. Be specific and give examples. c) The last step of the reaction, catalyzed by enzyme 3, includes three coenzymes and oxidation. Write the mechanism for this enzyme.

he immediate precursor to acetyl–CoA from glycolysis is pyruvate. a) Write the pathway (not the mechanism) for the series of steps for this conversion. Include structures for all coenzymes and reactants for each step. b) Discuss the mechanistic advantages offered by this multienzyme complex. Be specific and give examples. c) The last step of the reaction, catalyzed by enzyme 3, includes three coenzymes and oxidation. Write the mechanism for this enzyme.

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter23: Fatty Acid Catabolism

Section: Chapter Questions

Problem 21P: Using the ActiveModel for enoyl-CoA dehydratase, give an example of a case in which conserved...

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The PDH complex is a logical point of regulation in metabolism, as it links two major catabolic processes. Answer the following regarding the complex: a) Explain the advantage of E1, E2 and E3 working as a complex as opposed to separately. b) Explain the purpose of each of the three enzymes and their associated cofactors. c) NADH can inhibit the PDH complex directly or indirectly. What is the purpose of inhibition by NADH? d) Explain the differences between direct and indirect inhibition by NADH. Be sure to indicate the components involved and the mechanism of inhibition (impact on target component).
create a detailed flow chart or diagram that will illustrate all the important features of the glycolytic pathway. I want you to place in your flow chart or diagram the following important information like: 1. the reactants and products of each step, 2. enzymes involved in each step, 3. important by-products generated in some steps, 4. type of the reaction of each step, 5. and the outline of the two stages of the pathway. Also, discuss briefly (4 sentences) how Galactose and Fructose enter the glycolytic pathway.
D) Carbohydrate catabolism involves substrate-level phosphorylation. E) My answer is not here 27. The adduct acetoacetyl-acyl carrier protein is formed as an intermediate during fatty acid biosynthesis. The CO2 used to synthesize malonyl-S-CoA is lost. Would this help make the reaction more or less energetically favorable? A) Loss of CO2 increases entropy (AS) and therefore decreases the favorability of the reaction (AG). B) Loss of CO2 has no effect on entropy (AS) and therefore does not affect the favorability of the reaction (AG). C) Loss of CO2 increases entropy (AS) and therefore increases the favorability of the reaction (AG). D) Loss of CO2 decreases entropy (AS) and therefore decreases the favorability of the reaction (AG). E) Loss of CO2 decreases entropy (AS) and therefore increases the favorability of the reaction (AG).
In Bacillus subtilis, threonine is metabolized by the following sequence of reactions: (a) oxidation; (b) decarboxylation;(c) transamination; and (d) oxidation to produce pyruvate. Outline this sequence of steps, show the structures of thesubstances, use abbreviations for the cofactors, and show any enzyme-bound coenzymes. What type of enzyme bound intermediate is likely for reaction (d)?
Q) You are following the metabolism of aspartate that is equally labeled on all 4 carbons. Following a transamination aspartate is converted into oxaloacetate. Assuming the resulting Oxaloacetate is used as the substrate for the TCA cycle answer the following questions: a) Describe ALL the oxaloacetate molecules that would result from the first turn of the TCA cycle. b) Briefly describe how there is still label detected on the carboxylic acids even though they were removed as CO2 during the first turn of the cycle. (2 sentences MAX)
The krebs cycle has 8 enzymes: citrate synthase, aconitase, isocitrate dehyrogenase, a-ketoglutarate dehydrogenase, succinyl –CoA synthease, succinate dehyrogenase, fumarase and malate dehyrogenase. a)Write name the cofactors required by each enzyme reaction. b)For each enzyme determine which of the following deascribes the type of reactions catalyzed: condensation (Carbon-carbon bond formation), dehydration (Loss of water), hydration (addition of water), decarboxylation (loss of CO2), oxidation-reduction; subsrate level phospohorylation; isomerization.
Compare the regulation of phosphofuctokinase-1 (PFK- 1) activity and fructose 1,6- bisphosphatase in glycolysis. c) In the B-oxidation of a saturated, even chain fatty acid, four basic steps are involved. Describe these reactions using the degradation of palmitic acid as an example. d) e) Compare the steps involved in the formation of ketone bodies.
(a) Write a balanced equation for the conversion of aspartate into glucose through the intermediate oxaloacetate. Which coenzymes participate in this transformation? (b) Write a balanced equation for the conversion of aspartate into oxaloacetate through the intermediate fumarate
Some bacteria use the citric acid cycle intermediate, a-ketoglutarate, plus acetyl-CoA, as the starting point for lysine biosynthesis. The first part of this biosynthetic pathway uses the same chemical strategy found in the citric acid cycle. Propose a four-step pathway for the conversion of a-ketoglutarate to 2-oxoadipate. Draw the three missing intermediates, and indicate the chemistry involved in each reaction. Include any cofactors that you think might be required for specific steps.
Phosphoglycerate mutase (PGM) catalyzes the interconversion of 3-phosphoglycerate (3PG) and 2-phosphoglycerate (2PG) in the glycolytic and gluconeogenic pathways. a) To what enzyme class does PGM belong? b) There are two distinct classes of PGM, one which is dependent on 2,3-bisphosphoglycerate (2,3-BPG), dPGM, and one which is not, iPGM. dPGM uses acid base chemistry and a phosphorylated histidine residue to interconvert 3PG and 2PG. The dPGM reaction proceeds with formation of 2,3-BPG as an intermediate. Propose a mechanism for the dPGM-catalyzed conversion of 3PG to 2PG that is consistent with this information. c) What is the purpose of 2,3-BPG (i.e., why does dPGM require it)?
Determine whether the following statements are true or false:- a) The pentose phosphate pathway of glucose conversion is a supplier of NADPH (H +) for reductive syntheses. b) An overdose of insulin causes hypoglycemia in a patient with diabetes mellitus. c) Fructose-6-phosphate is an allosteric regulator of glycolysis.
In step 4 of glycolysis, F16BP is converted to GAP and DHAP. In the mechanism carried out by the aldolase (the enzyme the carries out this reaction) an active site lysine residue reacts with the substrates' carbonyl group to form a Schiff base. Briefly, what is the logic behind the formation of the Schiff base (i.e. why is it beneficial that the enzyme forms this Schiff base)?