1. The first step in the payoff phase of glycolysis is catalyzed by the enzyme glyceraldehyde 3-phosphatedehydrogenase, an enzyme that contains a nucleophilic cysteine playing a central role in the reaction.A) In the direction of gluconeogenesis, what reaction does this enzyme catalyze? AG° = -6.3 kcal/mol for thisreaction in the direction of gluconeogenesis. Based on what you know about the substrates involved,provide two chemical reasons as to why the AGO of this reaction is negative.

Gluconeogenesis is the metabolic pathway by which glucose is synthesised from the sources like…

Answered: 1. The first step in the payoff phase…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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The glucose/glucose-6-phosphate substrate cycle involves distinct reactions of glycolysis and gluconeogenesis that interconvert these two metabolites. Assume that under physiological conditions, [ATP] = [ADP]; [P;] = 1 mM. Consider the glycolytic reaction catalyzed by hexokinase: ATP + glucose ADP + glucose-6-phosphate AG = - 16.7 kJ/mol (a) Calculate the equilibrium constant (K) for this reaction at 298°K, and from that, calculate the maximum [glucose-6-phosphate]/ Iglucose] ratio that would exist under conditions where the reaction is still thermodynamically favorable. (b) Reversal of this interconversion in gluconeogenesis is catalyzed by glucose-6-phosphatase: glucose-6-phosphate + H20 = glucose + P AG" = -13.8 kJ/mol
The glucose/glucose-6-phosphate substrate cycle involves distinct reactions of glycolysis and gluconcogenesis that interconvert these two metabolites. Assume that under physiological conditions, [ATP] = [ADP] and [Pi] =1 mM. Consider the following glycolytic reaction catalyzed by hexokinase: ATP + glucose = AG' = -16.7 kJ/mol ADP + glucose-6-phosphate (a) Calculate the equilibrium constant (K) for this reaction at 298 K, and from that, calculate the maximum [glucose-6-phosphate]/[glucose] ratio that would exist under conditions where the reaction is still thermody- namically favorable. (b) The reverse of this interconversion in gluconeogenesis is catalyzed by glucose-6-phosphatase: glucose-6-phosphate + H,0 = glucose + P, AGr = -13.8 kJ/mol K= 262 for this reaction. Calculate the maximum ratio of [glucose]/ [glucose-6-phosphate] that would exist under conditions where the reaction is still thermodynamically favorable. (c) Under what cellular conditions would both directions in the…
The final step in the pathway for the synthesis of glucose from lactate (gluconeogenesis) is: Glucose-6-phosphate + H20 5 Glucose + Pi When glucose-6-phosphate is incubated with the proper enzyme and the reaction runs until equilibrium has been reached, the final concentrations are found to be: glucose-6-phosphate (0.035 mM), glucose (100 mM), and Pi (100 mM). Calculate AG" at 25°C and pH 7. 10:21 PM 4/21/2021 F5 F6 F7 F8 F10 F9 7 8. Backspace ーの
2. If glyceraldehyde-3-phosphate dehydrogenase in red blood cells is completely inhibited, which intermediates in glycolysis accumulate most? Please use the following equation and the provided information to explain your reasoning. AG=AG° + RTln [C][D]d [A] [B]¹ Fructose 1,6-bisphosphate → Glyceraldehyde 3-phosphate + Dihydroxyacetone phosphate The standard free energy for the above reaction is: AG" = +23.9 KJ/mol T° = 298 R = 8.314 J mol-¹ K-¹
Pyruvate carboxylase catalyzes the first step of gluconeogenesis. ATP + HCO3─ + pyruvate → oxaloacetate + ADP + Pi ∆G0’ = ─2.1 kJ mol-1 a) Calculate ΔG for this reaction under the following physiological conditions: 370C, pH 7 [pyruvate] = [HCO3─] = 4.0 mM [oxaloacetate]= 2.0 mM [ATP] = 3.5 mM [Pi] = 5.0 mM [ADP] = 1.8 mM
1.(a) ( ) Trace the course of [1,6-(C-14)-2,5-(C-13)]glucose that is first processed through glycolysis and proceeds into the TCA cycle. For the glycolysis part, use the diagram below to decide where glucose atoms end up in pyruvate. You need to illustrate only the structures of D-glucose, labeling the atoms, and of pyruvate, labeling the origin of the atoms in glucose and the distribution of the carbon isotopes in py- ruvate. After one round of the TCA cycle where will the labeled carbons be found? HO HO (b) (* CH₂OH Glucose HO + 2 NAD+ O + 2 NADH + 2 Pi 2 F0 + 2 ATP OH + 2 ADP 3 + 2 H₂O Pyruvate The formation of oxaloacetate in the TCA cycle is unfavorable with a AG'° = +29.7 kJ/mol. Write the reactions using structural formulas for the formation of oxaloacetate and for the subsequent reaction in the TCA cycle. What particular part of the subsequent reaction makes it very favorable and ensures that oxaloacetate is continually removed to make the next TCA intermediate?
2. If glyceraldehyde-3-phosphate dehydrogenase in red blood cells is completely inhibited, which intermediates in glycolysis accumulate most? Please use the following equation and the provided information to explain your reasoning. AG=AG° + RTln [C] [D]d [A] [B]' Fructose 1,6-bisphosphate → Glyceraldehyde 3-phosphate + Dihydroxyacetone phosphate The standard free energy for the above reaction is: AG" = +23.9 KJ/mol T° = 298 R = 8.314 J mol-¹ K-1
1.(a) ( ) Trace the course of [1,6-(C-14)-2,5-(C-13)]glucose that is first processed through glycolysis and proceeds into the TCA cycle. For the glycolysis part, use the diagram below to decide where glucose atoms end up in pyruvate. You need to illustrate only the structures of D-glucose, labeling the atoms, and of pyruvate, labeling the origin of the atoms in glucose and the distribution of the carbon isotopes in py- ruvate. After one round of the TCA cycle where will the labeled carbons be found? HO HO CH OH + 2 NAD+ O + 2 NADH + 2 Pj 2 + 2 ATP HO OH + 2 ADP CH3 + 2 H₂O Glucose Pyruvate
1.(a) ( ) Trace the course of [1,6-(C-14)-2,5-(C-13)]glucose that is first processed through glycolysis and proceeds into the TCA cycle. For the glycolysis part, use the diagram below to decide where glucose atoms end up in pyruvate. You need to illustrate only the structures of D-glucose, labeling the atoms, and of pyruvate, labeling the origin of the atoms in glucose and the distribution of the carbon isotopes in py- ruvate. After one round of the TCA cycle where will the labeled carbons be found? HO HO- СНЬОН + 2 NAD+ от + 2 NADH + 2 P₁ 2 + 2 ATP HO OH 2 ADP CH3 + 2 H₂O Glucose Pyruvate
A common procedure for determining the effectiveness of compounds as precursors of glucose in mammals is to starve the animal until the liverglycogen stores are depleted and then administer the compound in question. A substrate that leads to a net increase in liver glycogen is termed glucogenic, because it must first be converted to glucose 6-phosphate. Show by means of known enzymatic reactions which of the following substances are glucogenic.
In the degradation of glycogen, the purpose of the debranching enzyme is to remove the last four glucose molecules from branches structure of glycogen. It does this by catalyzing three different reactions. Use the equations below to answer parts a-c. Synthesis of α(1,6) link ΔG = +7.1 kJ Hydrolysis of α(1,4) link ΔG = ─15.5 kJ a)What are the three chemical reactions performed during the removal of the last four glucose molecules of the branching structure of glycogen? b) Calculate ΔG for each of the three reactions described in part a. c) Now calculate the overall energy change for the net reaction carried out by this enzyme. d) Why is this reaction favorable?
Consider the following interconversion, which occurs in glycolysis :(a) What is ΔG′° for the reaction ( K'eq measured at 25 °C)?(b) If the concentration of fructose 6-phosphate is adjusted to 1.5 M and that of glucose 6-phosphate is adjusted to 0.50 M, what is ΔG?(c) Why are ΔG′° and ΔG different?

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