A. The following experimental data was collected during a study of the catalytic activity of an intestinal peptidase with the substrate glycylglycine. Plot the data as a graph, and use it to estimate the Km and the Vmax for this enzyme. B. Now transform this data to plot it as a straight line (Lineweaver-Burk plot). Determine Km and the Vmax for this enzyme using this new plot. Do your results agree with the estimates made from the first graph of the raw data (from 2A)?  C. Now assume that the activity of this intestinal peptidase is regulated by covalent modification of its catalytically active amino acid. Upon phosphorylation, the Km of the catalyzed reaction has been observed to increase by a factor of 3 without any effect on its Vmax. Is the enzyme getting activated or inhibited upon phosphorylation? Justify your answer.  D. How will the Lineweaver-Burk plot of the phosphorylated enzyme differ from the plot of the unmodified enzyme (from 2B)? Give a rough graphical representation of the same.

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
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Question 2. Answer the following questions:


A. The following experimental data was collected during a study of the catalytic activity of an
intestinal peptidase with the substrate glycylglycine. Plot the data as a graph, and use it to
estimate the Km and the Vmax for this enzyme.

B. Now transform this data to plot it as a straight line (Lineweaver-Burk plot). Determine Km and
the Vmax for this enzyme using this new plot. Do your results agree with the estimates made from
the first graph of the raw data (from 2A)? 


C. Now assume that the activity of this intestinal peptidase is regulated by covalent modification
of its catalytically active amino acid. Upon phosphorylation, the Km of the catalyzed reaction has been observed to increase by a factor of 3 without any effect on its Vmax. Is the enzyme getting activated or inhibited upon phosphorylation? Justify your answer. 


D. How will the Lineweaver-Burk plot of the phosphorylated enzyme differ from the plot of the unmodified enzyme (from 2B)? Give a rough graphical representation of the same.

 

Substrate conc. (µM)
Reaction rate (µmol/min)
0.08
0.15
0.12
0.21
0.54
0.7
1.23
1.1
1.82
1.3
2.72
1.5
4.94
1.7
10.00
1.8
Transcribed Image Text:Substrate conc. (µM) Reaction rate (µmol/min) 0.08 0.15 0.12 0.21 0.54 0.7 1.23 1.1 1.82 1.3 2.72 1.5 4.94 1.7 10.00 1.8
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