Biochemistry
6th Edition
ISBN: 9781305577206
Author: Reginald H. Garrett, Charles M. Grisham
Publisher: Cengage Learning
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Chapter 18, Problem 24P
Based on your knowledge of the structure of NAD+ and an assumption that coenzyme dissociation is the rate limiting step of the alcohol dehydrogenase mechanism, hypothesize why a N249W mutation at the coenzyme binding site would increase the rate of catalysis.
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All dehydrogenases of glycolysis and the TCA cycle use NAD* (E° for NAD*/NADH
is -0.32V) as electron acceptor except succinate dehydrogenase (which uses FAD (E° for
FAD/FADH2 is 0.05V).
Based on AG° = -NFEº, show and state (1-2 sentences) why is FAD a more appropriate
electron acceptor than NAD* in the dehydrogenation of succinate (consider the E° values of
%3D
Uptake in Na+
Vmax
Uptake in absence of Na+
Vmax
substrate
K: (mM)
Kt (mM)
L-leucine
420
0.24
23
0.2
D-Leucine
310
4.7
5
4.7
L-valine
225
0.31
19
0.31
fumarate/succinate (E° = 0.031), NAD*/NADH, and the succinate dehydrogenase
FAD/FADH2).
In step 4 of glycolysis, F16BP is converted to GAP and DHAP. In the mechanism carried out
by the aldolase (the enzyme the carries out this reaction) an active site lysine residue reacts with the
substrates' carbonyl group to form a Schiff base. Briefly, what is the logic behind the formation of the
Schiff base (i.e. why is it beneficial that the enzyme forms this Schiff base)?
All the dehydrogenases of glycolysis and the citric acid cycle use NAD+ (E°' for NAD+/NADH is -0.32 V) as the electron acceptor, except succinate dehydrogenase, which uses covalently bound FAD (E°' for FAD/FADH2 is +0.050 V). Suggest why FAD is a more appropriate electron acceptor than NAD+ in the dehydrogenation of succinate, based on the E°' values of fumarate/succinate (E°' = +0.031 V)
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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