o 1. Protein tyrosine phosphatase enzymes are important regula- tory enzymes. Clinical trials show that inhibitors of these en- zymes can be important means for treating certain diseases, e.g., diabetes. Phosphatase enzymes catalyze removal of the phos- phoryl group from tyrosine residues of specific proteins convert- ing the phosphoryl group, i.e., PO3²-, into a phosphate through hydrolysis. As an example of a phosphatase enzyme, below are data collected to characterize protein tyrosine phosphatase-1B (PTP1B), an important enzyme regulating part of the pathway for uptake of glucose into cells. The activity was measured in the presence and absence of vanadate (VO43-), an inhibitor of the enzyme. An artificial substrate, fluores- cein diphosphate (FDP), shown on the right, was used in the experiments. Upon hydrolysis FDP forms the product fluorescein monophosphate (FMP) that absorbs light at 450 nm, allowing activity to be measured spectrophotometrically. The results are provided in the table below: Vo without vanadate (VO4³-) Vo with vanadate (VO4³-) (nm. s¹) 5.7 8.3 12.5 16.7 22.2 25.4 [FDP] (µM) 6.67 10 20 40 100 200 (nM. s-¹) 0.71 1.06 2.04 3.70 8.00 12.5 (a) Construct a Lineweaver-Burk plot using the data provided. Calculate KM and Vmax for PTP1B in the absence and in the presence of vanadate. (b) What kind of an inhibitor is vanadate (VO4³-)? Explain the criteria that define this type of inhibition and explain why structurally one would anticipate this type of inhibition.
o 1. Protein tyrosine phosphatase enzymes are important regula- tory enzymes. Clinical trials show that inhibitors of these en- zymes can be important means for treating certain diseases, e.g., diabetes. Phosphatase enzymes catalyze removal of the phos- phoryl group from tyrosine residues of specific proteins convert- ing the phosphoryl group, i.e., PO3²-, into a phosphate through hydrolysis. As an example of a phosphatase enzyme, below are data collected to characterize protein tyrosine phosphatase-1B (PTP1B), an important enzyme regulating part of the pathway for uptake of glucose into cells. The activity was measured in the presence and absence of vanadate (VO43-), an inhibitor of the enzyme. An artificial substrate, fluores- cein diphosphate (FDP), shown on the right, was used in the experiments. Upon hydrolysis FDP forms the product fluorescein monophosphate (FMP) that absorbs light at 450 nm, allowing activity to be measured spectrophotometrically. The results are provided in the table below: Vo without vanadate (VO4³-) Vo with vanadate (VO4³-) (nm. s¹) 5.7 8.3 12.5 16.7 22.2 25.4 [FDP] (µM) 6.67 10 20 40 100 200 (nM. s-¹) 0.71 1.06 2.04 3.70 8.00 12.5 (a) Construct a Lineweaver-Burk plot using the data provided. Calculate KM and Vmax for PTP1B in the absence and in the presence of vanadate. (b) What kind of an inhibitor is vanadate (VO4³-)? Explain the criteria that define this type of inhibition and explain why structurally one would anticipate this type of inhibition.
Biochemistry
6th Edition
ISBN:9781305577206
Author:Reginald H. Garrett, Charles M. Grisham
Publisher:Reginald H. Garrett, Charles M. Grisham
Chapter27: Metabolic Integration And Organ Specialization
Section: Chapter Questions
Problem 20P: Figure 27.3 illustrates the response of R (ATP-regenerating) and U (ATP-utilizing) enzymes to energy...
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![1. Protein tyrosine phosphatase enzymes are important regula-
tory enzymes. Clinical trials show that inhibitors of these en-
zymes can be important means for treating certain diseases, e.g.,
diabetes. Phosphatase enzymes catalyze removal of the phos-
phoryl group from tyrosine residues of specific proteins convert-
ing the phosphoryl group, i.e., PO3²-, into a phosphate through
hydrolysis. As an example of a phosphatase enzyme, below are
data collected to characterize protein tyrosine phosphatase-1B
(PTP1B), an important enzyme regulating part of the pathway for
uptake of glucose into cells. The activity was measured in the
presence and absence of vanadate (VO4³-), an inhibitor of the enzyme. An artificial substrate, fluores-
cein diphosphate (FDP), shown on the right, was used in the experiments. Upon hydrolysis FDP forms
the product fluorescein monophosphate (FMP) that absorbs light at 450 nm, allowing activity to be
measured spectrophotometrically. The results are provided in the table below:
Vo without vanadate (VO4³-)
Vo with vanadate (VO4³-)
(nM. s-¹)
(nM. s-¹)
5.7
0.71
8.3
1.06
12.5
2.04
16.7
3.70
22.2
8.00
25.4
12.5
[FDP] (µM)
6.67
10
20
40
100
200
(a)
Construct a Lineweaver-Burk plot using the data provided. Calculate KM and Vmax for
PTP1B in the absence and in the presence of vanadate.
(b)
What kind of an inhibitor is vanadate (VO4³-)? Explain the criteria that define this type of
inhibition and explain why structurally one would anticipate this type of inhibition.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F7e3218aa-1b65-42a2-9071-7edb43c3a555%2F63c9f8ef-0500-4c89-bf0e-2f5d4fea92e0%2F4qlnen9_processed.png&w=3840&q=75)
Transcribed Image Text:1. Protein tyrosine phosphatase enzymes are important regula-
tory enzymes. Clinical trials show that inhibitors of these en-
zymes can be important means for treating certain diseases, e.g.,
diabetes. Phosphatase enzymes catalyze removal of the phos-
phoryl group from tyrosine residues of specific proteins convert-
ing the phosphoryl group, i.e., PO3²-, into a phosphate through
hydrolysis. As an example of a phosphatase enzyme, below are
data collected to characterize protein tyrosine phosphatase-1B
(PTP1B), an important enzyme regulating part of the pathway for
uptake of glucose into cells. The activity was measured in the
presence and absence of vanadate (VO4³-), an inhibitor of the enzyme. An artificial substrate, fluores-
cein diphosphate (FDP), shown on the right, was used in the experiments. Upon hydrolysis FDP forms
the product fluorescein monophosphate (FMP) that absorbs light at 450 nm, allowing activity to be
measured spectrophotometrically. The results are provided in the table below:
Vo without vanadate (VO4³-)
Vo with vanadate (VO4³-)
(nM. s-¹)
(nM. s-¹)
5.7
0.71
8.3
1.06
12.5
2.04
16.7
3.70
22.2
8.00
25.4
12.5
[FDP] (µM)
6.67
10
20
40
100
200
(a)
Construct a Lineweaver-Burk plot using the data provided. Calculate KM and Vmax for
PTP1B in the absence and in the presence of vanadate.
(b)
What kind of an inhibitor is vanadate (VO4³-)? Explain the criteria that define this type of
inhibition and explain why structurally one would anticipate this type of inhibition.
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Step 1: Relation between Michaelis Menten equation and Lineweaver Burk Plot
VIEWStep 2: Lineweaver Burk plot for the given enzyme in presence of inhibitor
VIEWStep 3: Calculation of Km and vmax from the straight line equation in LB plot
VIEWStep 4: Type of inhibition exerted by vanadate
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