Becker's World of the Cell (9th Edition)
9th Edition
ISBN: 9780321934925
Author: Jeff Hardin, Gregory Paul Bertoni
Publisher: PEARSON
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Chapter 6, Problem 6.7PS
QUANTITATIVE More Enzyme Kinetics. The galactose formed in Reaction 6-17 can be phosphorylated by the transfer of a phosphoryl group from ATP, a reaction catalyzed by the enzyme galactokinase:
Assume that you have isolated the galactokinase enzyme and have determined its kinetic parameters by varying the concentration of galactose in the presence of a constant, high (i.e., saturating) concentration of ATP. The double-reciprocal (Lineweaver–Burk) plot of the data is shown as Figure 6-17.
Figure 6-17 Double-Reciprocal Plot for the Enzyme Galactokinase. See Problem 6-7.
(a) What is the Km of galactokinase for galactose under these assay conditions? What does Km tell us about the enzyme?
(b) What is the Vmax of the enzyme under these assay conditions? What does Vmax tell us about the enzyme?
(c) Assume that you now repeat the experiment, but with the ATP concentration varied and galactose present at a constant, high concentration. Assuming that all other conditions aremaintained as before, would you expect to get the same Vmax value as in part b? Why or why not?
(d) In the experiment described in part c, the Km value turned out to be very different from the value determined in part b. Can you explain why?
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6-25
substrate-band enzyme concentrations. The the
turnover number is equal to umax-
b)
V=Umax •57(Km+S)
anstont
For an enzyme that displays Michaelis-Menten kinetics, what is
the reaction velocity, V (as a percentage of Vmax), observed at
the following values?
a)
[S] = KM
C)
d)
e)
[S] = 0.5KM
[S] = = 0.1KM
[S] = 2KM
[S] = 10KM
w
reactores
-maximumrate of reaction
boteles conc.
Would you expect the structure of a competitive inhibitor of a
given enzyme to be similar to that of its substrate?
Synthetic stoichiometries. What is the stoichiometry of the synthesis of...
(a) ribose 5-phosphate from glucose 6- phosphate without the concomitant generation of NADPH?
(b) NADPH from glucose 6-phosphate without the concomitant formation of pentose sugars?
Select all that apply.
What is true about the conformational aspects of coupling?
O The proton gradient is involved in the release of bound ATP from the synthase as a result of conformational change.
O The conformational states interconvert as a result of proton flux through the synthase.
There are two sites for substrate on the synthase and two possible conformational states: open (0) and tight-binding (T).
Dinitrophenol binds to and inhibits ATP synthase conformational changes, thus inhibiting ATP synthesis.
The Fo portion of ATP synthase acts as a rotary motor.
Chapter 6 Solutions
Becker's World of the Cell (9th Edition)
Ch. 6 - Gasoline is highly combustible yet doesnt burst...Ch. 6 - How can an enzyme recognize and bind one specific...Ch. 6 - Prob. 1QCh. 6 - You work at a biotechnology company and are...Ch. 6 - Why do enzymes need to be regulated? By what...Ch. 6 - The Need for Enzymes. You should now be in a...Ch. 6 - Prob. 6.2PSCh. 6 - Prob. 6.3PSCh. 6 - Temperature and pH Effects. Figure 6-4 illustrates...Ch. 6 - MichaelisMenten Kinetics. Figure 6-16 represents a...
Ch. 6 - Prob. 6.6PSCh. 6 - QUANTITATIVE More Enzyme Kinetics. The galactose...Ch. 6 - QUANTITATIVE Turnover Number. Carbonic anhydrase...Ch. 6 - Inhibitors: Wrong Again. For each of the following...Ch. 6 - What Type of Inhibition? A new mucinase enzyme was...Ch. 6 - Prob. 6.11PSCh. 6 - Prob. 6.12PSCh. 6 - Prob. 6.13PS
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