2. The kinetics of an enzyme are measured as a function of substrate concentration in the presence and absence of 100 uM inhibitor. Show calculations, include the table of values needed to make your graphs and provide full explanations for each of the following. Velocity (UM/minute) [S] (UM) No inhibitor Inhibitor 3 10.4 2.1 5 14.5 2.9 10 22.5 4.5 30 33.8 6.8 90 40.5 8.1 i) Calculate the values of Km and Vmax in the absence of the inhibitor? Show all calculations. Circle your final answers. Make sure units are included II) What are the values of Km and Vmax in the presence of the inhibitor? Show all calculations. Circle your final answers. Make sure units are included. iii) What type of inhibition is this? Explain your reasoning

Principles of Modern Chemistry
8th Edition
ISBN:9781305079113
Author:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler
Publisher:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler
Chapter14: Chemical Equilibrium
Section: Chapter Questions
Problem 88AP
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2. The kinetics of an enzyme are measured as a function of substrate concentration in the presence and
absence of 100 uM inhibitor. Show calculations, include the table of values needed to make your graphs
and provide full explanations for each of the following.
Velocity (uM/minute)
[S] (UM)
No inhibitor
Inhibitor
3
10.4
2.1
5
14.5
2.9
10
22.5
4.5
30
33.8
6.8
90
40.5
8.1
i) Calculate the values of Km and Vmax in the absence of the inhibitor? Show all calculations. Circle your
final answers. Make sure units are included
II) What are the values of Km and Vmax in the presence of the inhibitor? Show all calculations. Circle
your final answers. Make sure units are included.
iii) What type of inhibition is this? Explain your reasoning
Transcribed Image Text:2. The kinetics of an enzyme are measured as a function of substrate concentration in the presence and absence of 100 uM inhibitor. Show calculations, include the table of values needed to make your graphs and provide full explanations for each of the following. Velocity (uM/minute) [S] (UM) No inhibitor Inhibitor 3 10.4 2.1 5 14.5 2.9 10 22.5 4.5 30 33.8 6.8 90 40.5 8.1 i) Calculate the values of Km and Vmax in the absence of the inhibitor? Show all calculations. Circle your final answers. Make sure units are included II) What are the values of Km and Vmax in the presence of the inhibitor? Show all calculations. Circle your final answers. Make sure units are included. iii) What type of inhibition is this? Explain your reasoning
1. Penicillin is hydrolyzed and thereby rendered inactive penicillinase, an enzyme present in some
penicillin-resistant bacteria. The molecular weight of this enzyme in Staphylococcus aureus is 29.6 kilo
Daltons (29.6 kg/mole or 29,600 g/mole or 29,600 ng/nmole) The amount of penicillin hydrolyzed in 2
minute in a 10-mL solution containing 109 g (1 ng) of purified penicillinase was measured as a function
of the concentration of penicillin. Assume that the concentration of penicillin does not change
appreciably during the assay. [Hint: Convert everything to the same concentration terms]
Show all calculations and include spreadsheets and graphs to determine Km, Vmax and kcat for this
enzyme. Make sure your final answers have correct units.
[Another hint: Note that [S] and amount hydrolyzed are already in concentration terms. So you don't
need to worry about the volume for calculating [S] and V. ]
Penicillin concentration (microM)
Amount hydrolyzed (nanoM)
1
110
3
250
5
340
10
450
30
580
50
600
i.
Plot Vo versus [S] and 1/Vo vs 1/[S] for these data. Does penicillinase appear to obey
Michaelis-Menten kinetics? Explain. If so, calculate the value of Km? Show all calculations.
Circle your final answer.
Calculate the value of Vmax? Show all calculations. Circle your final answer.
What is the turnover number of penicillinase under these experimental conditions? Assume
three active sites per enzyme molecule. Show all calculations. Circle your final answer.
iv.
What is the catalytic efficiency of penicillinase under these experimental conditions? Show
all calculations. Circle your final answer.
1
ii.
Transcribed Image Text:1. Penicillin is hydrolyzed and thereby rendered inactive penicillinase, an enzyme present in some penicillin-resistant bacteria. The molecular weight of this enzyme in Staphylococcus aureus is 29.6 kilo Daltons (29.6 kg/mole or 29,600 g/mole or 29,600 ng/nmole) The amount of penicillin hydrolyzed in 2 minute in a 10-mL solution containing 109 g (1 ng) of purified penicillinase was measured as a function of the concentration of penicillin. Assume that the concentration of penicillin does not change appreciably during the assay. [Hint: Convert everything to the same concentration terms] Show all calculations and include spreadsheets and graphs to determine Km, Vmax and kcat for this enzyme. Make sure your final answers have correct units. [Another hint: Note that [S] and amount hydrolyzed are already in concentration terms. So you don't need to worry about the volume for calculating [S] and V. ] Penicillin concentration (microM) Amount hydrolyzed (nanoM) 1 110 3 250 5 340 10 450 30 580 50 600 i. Plot Vo versus [S] and 1/Vo vs 1/[S] for these data. Does penicillinase appear to obey Michaelis-Menten kinetics? Explain. If so, calculate the value of Km? Show all calculations. Circle your final answer. Calculate the value of Vmax? Show all calculations. Circle your final answer. What is the turnover number of penicillinase under these experimental conditions? Assume three active sites per enzyme molecule. Show all calculations. Circle your final answer. iv. What is the catalytic efficiency of penicillinase under these experimental conditions? Show all calculations. Circle your final answer. 1 ii.
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