d. What type of inhibition is exhibited against NAD* as a cofactor? Describe what is going on in this type of inhibition. e. Referring to the mechanism below, what step is pyrazole likely interfering with given your answers in c and d? 1. binding of NAD+ to the enzyme, LADH 2. binding of C₂H5OH to LADH 3. Oxidation of C₂H5OH (This is the reaction step) and product dissociation 4. Dissociation of NADH from LADH NAD + LADH NAD LADH + C₂H5OH NAD LADH C₂H5OH NADH LADH NAD LADH k2 NAD LADH C₂H5OH ОН NADH LADH + NADH+ LADH CH3CHO + H
d. What type of inhibition is exhibited against NAD* as a cofactor? Describe what is going on in this type of inhibition. e. Referring to the mechanism below, what step is pyrazole likely interfering with given your answers in c and d? 1. binding of NAD+ to the enzyme, LADH 2. binding of C₂H5OH to LADH 3. Oxidation of C₂H5OH (This is the reaction step) and product dissociation 4. Dissociation of NADH from LADH NAD + LADH NAD LADH + C₂H5OH NAD LADH C₂H5OH NADH LADH NAD LADH k2 NAD LADH C₂H5OH ОН NADH LADH + NADH+ LADH CH3CHO + H
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
Related questions
Question
Solve for d and e
![3. Pyrozole has been proposed as a possible nontoxic inhibitor of LADH-catalyzed ethanol oxidation. Its
kinetics have been studied and, in 2 separate experiments, the velocity of the reaction was measured as a
function of [C₂H5OH] and of [NAD*]. The data is given in the tables below.
[C₂H5OH] varies, [LADH]= 4µg/ml, [NAD+] = 350 µM, pH=7.4, 23.5C
[C₂H5OH]
Vo (relative
Vo (relative units)
1x10-5 M pyrazole
M
units)
No pyrazole
2.1
1.8
1.5
1.35
0.008
0.002
0.001
0.00067
[NAD+] varies, [LADH]= 4µg/ml, [C₂H5OH]= 5 mM, pH=7.4, 23.5C
[NAD+]
Vo (relative units)
4x10-5 M pyrazole
Vo (relative
units)
No pyrazole
0.00011
1.7
0.000056
1.4
0.000033
1.3
0..000017 0.95
1.7
1.0
0.69
0.52
0.85
0.71
0.63
0.47
a. Plot the data as Lineweaver-Burke plots on two separate graphs.
b. Determine the Km values for [C₂H5OH] and of [NAD+]. (You can't find Vmax because the exact units of Vo
are not provided)
c. What type of inhibition is exhibited by pyrazole against C₂H5OH is a substrate? Describe what is going on in
this type of inhibition.
d. What type of inhibition is exhibited against NAD+ as a cofactor? Describe what is going on in this type of
inhibition.
e. Referring to the mechanism below, what step is pyrazole likely interfering with given your answers in c and
d?
2. binding of C₂H5OH to LADH
1. binding of NAD+ to the enzyme, LADH
3. Oxidation of C₂H5OH (This is the reaction
step) and product dissociation
4. Dissociation of NADH from LADH
NAD*
+ LADH
NAD LADH + C₂H5OH
+
NAD LADH C₂H5OH
NADH LADH
k4
-4
NAD LADH
+
NAD LADH C₂H5OH
ОН
NADH LADH +
NADH+LADH
CH, CHO
+ H
JL](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff123c09d-ccbd-492d-9b0f-c8892232526f%2F9ff53e63-edab-448f-a526-0aa2a242290d%2Fhj8pb8j_processed.png&w=3840&q=75)
Transcribed Image Text:3. Pyrozole has been proposed as a possible nontoxic inhibitor of LADH-catalyzed ethanol oxidation. Its
kinetics have been studied and, in 2 separate experiments, the velocity of the reaction was measured as a
function of [C₂H5OH] and of [NAD*]. The data is given in the tables below.
[C₂H5OH] varies, [LADH]= 4µg/ml, [NAD+] = 350 µM, pH=7.4, 23.5C
[C₂H5OH]
Vo (relative
Vo (relative units)
1x10-5 M pyrazole
M
units)
No pyrazole
2.1
1.8
1.5
1.35
0.008
0.002
0.001
0.00067
[NAD+] varies, [LADH]= 4µg/ml, [C₂H5OH]= 5 mM, pH=7.4, 23.5C
[NAD+]
Vo (relative units)
4x10-5 M pyrazole
Vo (relative
units)
No pyrazole
0.00011
1.7
0.000056
1.4
0.000033
1.3
0..000017 0.95
1.7
1.0
0.69
0.52
0.85
0.71
0.63
0.47
a. Plot the data as Lineweaver-Burke plots on two separate graphs.
b. Determine the Km values for [C₂H5OH] and of [NAD+]. (You can't find Vmax because the exact units of Vo
are not provided)
c. What type of inhibition is exhibited by pyrazole against C₂H5OH is a substrate? Describe what is going on in
this type of inhibition.
d. What type of inhibition is exhibited against NAD+ as a cofactor? Describe what is going on in this type of
inhibition.
e. Referring to the mechanism below, what step is pyrazole likely interfering with given your answers in c and
d?
2. binding of C₂H5OH to LADH
1. binding of NAD+ to the enzyme, LADH
3. Oxidation of C₂H5OH (This is the reaction
step) and product dissociation
4. Dissociation of NADH from LADH
NAD*
+ LADH
NAD LADH + C₂H5OH
+
NAD LADH C₂H5OH
NADH LADH
k4
-4
NAD LADH
+
NAD LADH C₂H5OH
ОН
NADH LADH +
NADH+LADH
CH, CHO
+ H
JL
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