Upon careful analysis, you discover that mutation causes the patient's glucokinase tobehave exactly like hexokinase (i.e. an increased affinity for glucose with decreased Kmvalue and a decrease in the Vmax). Which of the following lines on the Lineweaver-Burk Plot(Figure 1) best represents the mutated enzyme compared to normal glucokinase? Explain.BNormal Glucokinase[V]1[S]Figure 1

LB plot is called double reciprocal plot as it is plotted by taking inverse of substrate…

Answered: Upon careful analysis, you discover…

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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If glucokinase has a higher Km for glucose than does hexokinase, but can only bind to D-glucose, while hexokinase can bind to several hexose sugars (like D-glucose, D-mannose, and D-fructose), then: glucokinase has both a higher affinity and a higher specificity for D-glucose than does hexokinase glucokinase has both a lower affinity and a lower specificity for D-glucose than does hexokinase glucokinase has a higher affinity but a lower specificity for D-glucose than does hexokinase glucokinase has a lower affinity but a higher specificity for D-glucose than does hexokinase all of the above
For each of the following situations, predict the major consequences for glycogen metabolism. Explain your logic in a few sentences. Consider the effect on both glycogen degradation and glycogen synthesis where relevant. Will the amount of glycogen be higher or lower than normal? Mutation of S116C in phosphoglucomutase. (This notation means the following: S116 is the normal amino acid in this enzyme. It has been mutated to 116C.) Loss of the gene for GSK3. Effect of the coenzyme analog below. (Hint: how does the normal coenzyme operate and why can’t this analog react in the same way?)
Patients with a form of early-onset diabetes were found to carry a variety of mutations reducing the function of the glucokinase (GK) enzyme. These patients are heterozygous for one of the mutations, and thus show only partial rather than complete loss of GK activity. Answer the following questions about these patients. 1. How would blood sugar levels likely be affected in GK-mutation patients? Briefly explain your choice (25 words or less) a. Higher than normal b. Normal C. Lower than normal d. Cannot predict based on the provided information
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

Explain why people with a hereditary deficiency of carnitine acyltransferase II have muscle weakness. Why are the symptoms more severe during fasting? (Keep your answer to at least a paragraph)
In muscle tissue, the rate of conversion of glycogen to glucose 6-phosphate is determined by the ratio of phosphorylase a (active) to phosphorylase b (less active). Determine what happens to the rate of glycogen breakdown if a muscle preparation containing glycogen phosphorylase is treated with: (a) phosphorylase kinase and ATP; (b) PP1; (c) epinephrine
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 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
Fructose 1,6-bisphosphatase (FBPase) is a key enzyme in gluconeogenesis. The mammalian enzyme is tetrameric, negatively regulated by both Fructose 2,6-bisphosphate and AMP. Propose three (3) distinct models for how these molecules regulate FBPase activity. Also, describe how the enzyme might differentiate between Fructose 1,6 bisphosphate and Fructose 2,6-bisphosphate binding to the allosteric site on the enzyme with particular emphasis on amino acids comprising the allosteric binding site(s).
The Vmax of muscle glycogen phosphorylase is much larger than that of the liver enzyme. Discuss the functional signifi cance of this phenomenon.
In McArdle's disease, a type of glycogen storage disease, there is a total deficiency of muscle glycogen phosphorylase. An individual with such disease is not able to exercise strenuously and experiences muscle cramps. Exercise leads to higher than normal levels of cellular ADP and Pi. Besides, lactic acid does not accumulate, as in the case of a normal individual. Explain the chemical imbalances shown in McArdle's discase.
Type VI glycogen storage disease (Hers disease) is a rare metabolic disorder caused by lack of phosphorylase kinase in the liver. In your own words describe how each of the following metabolic parameters/observations will be affected/unaffected in a person with Type VI GSD (a) Blood glucose levels, after fasting (e.g. before breakfast). (b) Blood glucose levels, immediately following a meal. (c) Storage of glycogen in the liver and muscles. (d) ATP concentration in the muscles

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