(a) The Michaelis-Menten equation was derived for the "hypothetical" reaction written below involving only one intermediate: E + S ES E + P [1] A generalized representation of an enzyme catalyzed reaction that is likely to be more accurate and closer to reality can be written as follows: E + S P [2] E + ¿ where the arrows in the forward and backward directions indicate at least partial reversibility for each step, 12 and 13 represent reaction intermediates sequentially formed after the noncovalent Michaelis complex ES, and EP indicates an enzyme-product complex. Nonetheless, the Michaelis equation ES 12 13 EP V Kcat [Eo] [SO] (KM + [SO]) can be used to determine kinetic parameters under steady-state conditions. Explain. (b) Determination of kinetic parameters governing an enzyme catalyzed reaction under steady-state conditions leads to estimation of values for kcat, KM, and kcat/KM. Define each parameter and indicate which are determined according to the quality of the experimental data. Explain how fixing the value of these two parameters constrains the value of the third. Since steady-state kinetic parameters are determined on the basis of initial velocity data (vo) and initial substrate concentration ([So]), leading to an estimate of Vmax, explain the relationship between kcat and Vmax. What is the critical experimental condition that validates use of this relationship?
(a) The Michaelis-Menten equation was derived for the "hypothetical" reaction written below involving only one intermediate: E + S ES E + P [1] A generalized representation of an enzyme catalyzed reaction that is likely to be more accurate and closer to reality can be written as follows: E + S P [2] E + ¿ where the arrows in the forward and backward directions indicate at least partial reversibility for each step, 12 and 13 represent reaction intermediates sequentially formed after the noncovalent Michaelis complex ES, and EP indicates an enzyme-product complex. Nonetheless, the Michaelis equation ES 12 13 EP V Kcat [Eo] [SO] (KM + [SO]) can be used to determine kinetic parameters under steady-state conditions. Explain. (b) Determination of kinetic parameters governing an enzyme catalyzed reaction under steady-state conditions leads to estimation of values for kcat, KM, and kcat/KM. Define each parameter and indicate which are determined according to the quality of the experimental data. Explain how fixing the value of these two parameters constrains the value of the third. Since steady-state kinetic parameters are determined on the basis of initial velocity data (vo) and initial substrate concentration ([So]), leading to an estimate of Vmax, explain the relationship between kcat and Vmax. What is the critical experimental condition that validates use of this relationship?
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
![(a)
The Michaelis-Menten equation was derived for the "hypothetical" reaction written
below involving only one intermediate:
E + S
ES
E
+
P
[1]
A generalized representation of an enzyme catalyzed reaction that is likely to be more accurate and
closer to reality can be written as follows:
E + S
P [2]
E +
¿
where the arrows in the forward and backward directions indicate at least partial reversibility for each
step, 12 and 13 represent reaction intermediates sequentially formed after the noncovalent Michaelis
complex ES, and EP indicates an enzyme-product complex. Nonetheless, the Michaelis equation
ES
12
13
EP
V
Kcat [Eo] [SO] (KM + [SO])
can be used to determine kinetic parameters under steady-state conditions. Explain.
(b)
Determination of kinetic parameters governing an enzyme catalyzed reaction under
steady-state conditions leads to estimation of values for kcat, KM, and kcat/KM. Define each parameter
and indicate which are determined according to the quality of the experimental data. Explain how
fixing the value of these two parameters constrains the value of the third. Since steady-state kinetic
parameters are determined on the basis of initial velocity data (vo) and initial substrate concentration
([So]), leading to an estimate of Vmax, explain the relationship between kcat and Vmax. What is the
critical experimental condition that validates use of this relationship?](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F3600976f-5a74-4553-80f1-af12fd18d682%2F63dbe4f4-0ff1-4044-bfd8-4d8a49f55bc4%2Flqh3gg_processed.png&w=3840&q=75)
Transcribed Image Text:(a)
The Michaelis-Menten equation was derived for the "hypothetical" reaction written
below involving only one intermediate:
E + S
ES
E
+
P
[1]
A generalized representation of an enzyme catalyzed reaction that is likely to be more accurate and
closer to reality can be written as follows:
E + S
P [2]
E +
¿
where the arrows in the forward and backward directions indicate at least partial reversibility for each
step, 12 and 13 represent reaction intermediates sequentially formed after the noncovalent Michaelis
complex ES, and EP indicates an enzyme-product complex. Nonetheless, the Michaelis equation
ES
12
13
EP
V
Kcat [Eo] [SO] (KM + [SO])
can be used to determine kinetic parameters under steady-state conditions. Explain.
(b)
Determination of kinetic parameters governing an enzyme catalyzed reaction under
steady-state conditions leads to estimation of values for kcat, KM, and kcat/KM. Define each parameter
and indicate which are determined according to the quality of the experimental data. Explain how
fixing the value of these two parameters constrains the value of the third. Since steady-state kinetic
parameters are determined on the basis of initial velocity data (vo) and initial substrate concentration
([So]), leading to an estimate of Vmax, explain the relationship between kcat and Vmax. What is the
critical experimental condition that validates use of this relationship?
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