Biochemistry
6th Edition
ISBN: 9781305577206
Author: Reginald H. Garrett, Charles M. Grisham
Publisher: Cengage Learning
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Textbook Question
Chapter 18, Problem 22P
Based on your residing of this chapter, what would you expect to be the most immediate effect oil glycolysis, if the steady-state concentration of gJucose-6-P were 8.3 mM instead of 0.083 mM?
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The effect of temperature on the hydrolysis of lactose by a ß-galactosidase is shown
below in Table 1. The temperature coefficient, Q10 is the factor by which the rate
increases by raising the temperature 10°C. The universal gas constant, R is 8.314
J/mol.K.
(a)
(b)
Table 1: Data of Vmax over temperature
T (°C)
20
30
35
40
45
Vmax (umoles/min.mg protein)
4.50
8.65
11.80
15.96
21.36
Plot the graph of In Vm vs 1/T using any spreadsheet software (include all
appropriate labels and equation).
Calculate the activation energy Ea and temperature coefficient Q10.
A researcher purifies a mutant version of the glucokinase enzyme. She combines the purified glucokinase with glucose and ATP
to produce glucose 6-phosphate. She records the initial velocity (V) of glucose 6-phosphate production at various substrate
concentrations ([S]). She determines a Michaelis-Menten constant (Km) of 6.2 mM for the mutant enzyme.
[S] (mM)
µmol
min
5
1.03
10
1.42
50
2.05
100
2.17
Calculate the maximum velocity (Vmax) of the mutant glucokinase to one decimal place using the Michaelis-Menten equation.
umol
Vmax
min
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
Chapter 18 Solutions
Biochemistry
Ch. 18 - Characterizing Glycolysis List the reactions of...Ch. 18 - Radiotracer Labeling of Pyruvate from Glucose...Ch. 18 - Effects of Changing Metabolite Concentrations on...Ch. 18 - Prob. 4PCh. 18 - Prob. 5PCh. 18 - The Reactions and Meehanisms of the Leloir Pathway...Ch. 18 - The Effect of lodoacetic Acid on the...Ch. 18 - Prob. 8PCh. 18 - Comparing Glycolysis Entry Points for Sucrose...Ch. 18 - Prob. 10P
Ch. 18 - Prob. 11PCh. 18 - Prob. 12PCh. 18 - Prob. 13PCh. 18 - Energetic of Fructose-1 ,6-bis P Hydrolysis...Ch. 18 - Prob. 15PCh. 18 - Energetics of the Hexokinase Reaction The...Ch. 18 - Prob. 17PCh. 18 - Distinguishing the Mechanisms of Class I and Class...Ch. 18 - Prob. 19PCh. 18 - Understanding the Mechanism of Hemolytic Anemia...Ch. 18 - Prob. 21PCh. 18 - Based on your residing of this chapter, what would...Ch. 18 - Examine the ActiveModel for alcohol dehydrogenase...Ch. 18 - Based on your knowledge of the structure of NAD+...Ch. 18 - Using the ActiveModel for phosphofructokinase...
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