19. The AG, the standard free-energy change, for the isomerization of dihydroxyacetone phosphate(DHAP) to glyceraldehyde 3-phosphate (GAP) is +7.55 kJ/mol. The reaction shown below iscatalyzed by an enzyme called Triose Phosphate Isomerase (TPI).OHOOHDHAPOHTPIOHM+OHGAPOHThis reaction takes place in glycolysis. At equilibrium, the ratio of GAP to DHAP is 0.0475 at 25°Cand pH 7.00. Equilibrium constant, Keq = 0.0475.A) Is the above reaction endergonic or exergonic (going from left to right) under the givenexperimental conditions? Why?B) Can the above reaction occur spontaneously under the given experimental conditions? Why orwhy not?

The rate of a chemical reaction refers to how quickly reactants are converted into products over…

Answered: 19. The AG, the standard free-energy…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter25: Nitrogen Acquisition And Amino Acid Metabolism

Section: Chapter Questions

Problem 22P

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Triose phosphate isomerase In a key reaction of glycolysis, dihydroxyacetone phosphate (DHAP) is isomerized into glyceraldehyde 3-phosphate (G3P) by the action of the enzyme triose phosphate isomerase: CH₂OH C=O CH₂OPO3²- DHAP CHO HC-OH CH₂OPO3²- G3P AG°¹ +7.5 kJ/mol Because AG is positive, the equilibrium lies to the left. (a) Calculate the equilibrium constant for this reaction, assuming a temperature of 37 °C. (b) In the cell, depletion of G3P makes the reaction proceed. What is the value of AG if the concentration of G3P is kept at 1/100 of the value of the concentration of DHAP? C ZOOM +
24. Hexokinase catalyzes the phosphorylation of glucose from ATP, yielding glucose-6-P and ADP. The standard-state free energy change for hydrolysis of glucose-6-P is -13.9 kJ/mol. Calculate the standard-state free energy change and equilibrium constant for the hexokinase reaction. AG" for ATP hydrolysis -31.5 kJ/mol
When grown anaerobically on glucose, yeast (S. cerevisiae) converts pyruvate to acetaldehyde, then reduces acetaldehyde to Pethanol using electrons from NADH. Write the chemical equation for the reaction that reduces acetaldehyde (CH3CHO) to ethanol (CH3CH2OH). The table provides the standard reduction potential, E', of the relevant half-reactions. Half-reaction Acetaldehyde + 2 H+ + 2e¯ → ethanol NAD+ + 2H+ + 2e¯ → NADH + H+ E'° (V) -.197 -.320 Calculate the equilibrium constant, K'eq, at 25.0 °C for the reaction that reduces acetaldehyde to ethanol. K'e ×10 = eq
The standard free energy change for this reaction in the direction written is +23.8 kuimol. The tabie shows the concentrations of the three intermediates in the hepatocyte of a mammal. Intermediate Concentration (M) Fructose 1.0-bisphosphate 0.000028 Gyoeraldehyde 3phosphate 0.0000068 Ditydroxyacetone phosphate 0.000032 At body temperature (37 "C). what is the actual free energy change for the reaction (in kimol) ?
In humans, the biosynthesis of L-glutamine is catalyzed by the L-glutamine synthetase. The global reaction can be written as follows: ATP + glutamate + NH3 ADP + phosphate + glutamine The A,Gº' value for this reaction is -16.3 kJ.mol-1 (from left to right). 1- Explain the significance this information. 2- This reaction can be considered as the sum of two component reactions which are exergonic and endergonic, respectively, under standard conditions. Write these two component reactions and evaluate A,Gº of the endergonic reaction. Data: A,Gº of ATP hydrolysis = -30.4 kJ mol-¹
In working skeletal muscle under anaerobic conditions, glyceraldehyde 3-phosphate is converted to pyruvate (the payoff phase of glycolysis), and the pyruvate is reduced to lactate. Write balanced biochemical equations for all the reactions in this process, with the standard free-energy change for eachreaction. Then write the overall or net equation for the payoff phase of glycolysis (with lactate as the end product), including the net standard free-energy change.
The enzyme aldolase catalyzes the reaction shown in the glycolytic pathway: Fructose 1,6-bisphosphate dihydroxyacetone phosphate + glyceraldehyde 3-phosphate The AG" for the reaction is +23.8 kJ mol¯¹ (+5.7 kcal mol−¹), whereas the AG in the cell is −1.3 kJ mol¯¹ (−0.3 kcal mol¯¹). Calculate the ratio of products to reactants under standard (equilibrium) conditions at 37°C. [products] [reactants] 7 x10-5 [products] [reactants] Incorrect Aldolase ===== Calculate the ratio of products to reactants under intracellular conditions at 37°C. 4 ×10-5 Incorrect Complete the statement using your results. under standard conditions under intracellular conditions A reaction that is endergonic under standard conditions can be converted into an exergonic reaction by maintaining the ratio of products to reactants below the equilibrium value.
5) In an experiment to investigate the inhibition of the enzyme-glucosidase the following data for the rates of reaction with glucopyranoside for various substrate concentrations was obtained. By constructing a Leaver-Burk plot, determine the value of the Michaelis constant. [S]/ (10-6 mol dm-3) v/ (10-3 mol dm-3 s-1) 1.00 2.00 3.00 4.00 16.7 33.3 41.1 49.8
The standard Gibbs (free) energy of reaction (A,Gº') of the following reaction is equal to zero (at 25 °C and pH 7) pyruvate + aspartate Pyruvate, aspartate and L-alanine are mixed each at a concentration of 1 mM, without oxaloacetate. Calculate the molar concentrations of each compound when the reaction reaches equilibrium. oxaloacétate + L-alanine
Acetyl CoA + 2H* + 2e = pyruvate + COASH E = -0.48 V Ubiquinone + 2H* + 2e = Ubiquinol E" = +0.04 V Consider the redox rxn wherein a pair of e passes from pyruvate to ubiquinone. Calculate the change in standard Gibbs free energy (kJ/mol). Report answer to two decimal places.
The turnover number of the enzyme fumarase that catalyzes the reaction, Fumarate + H20 ===→ L-malate, is 2.5 x 103 S - l and Km = 4.0 X 10- 6 mol/L. Calculate the rate of conversion of fumarate to L-malate if the fumarase concentration is 1.0 x 1 0 - 6 mol/L and the fumarate concentration is 2.04 x 10- 4 mol/L.
Consider the following list of phosphorylated compounds with their free energy changes of phosphate hydrolysis: Glucose-1-phosphate (-5.0 kcal/mol), PEP (-14.8 kcal/mole), 1,3-bisphosphoglycerate (-11.8 kcal/mole) and Glucose-6-Phosphate (-3.3 kcal/mol). Given that the free energy change of ATP hydrolysis is -7.3 kcal/mole, which of these molecules be directly synthesized by the transfer of a phospho- group from ATP? 1,3-bisphosphoglycerate Glucose-6-phosphate All of those phosphorylated compounds. PEP Glucose-1-phosphate

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