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7: Enzyme Kinetics

Students determine Vmax and Km from substrate concentration data, interpret Michaelis-Menten and Lineweaver-Burk plots, and calculate enzyme efficiency using kcat.

LibreTexts reference: Unit 2, Chapter 2: Enzyme Kinetics LibreTexts

Michaelis-Menten Constant (Km) from Enzyme Activity Data

Click to show Michaelis-Menten Constant (Km) from Enzyme Activity Data example problem

Michaelis-Menten question. The following question refers to the table (below) of enzyme activity.

substrate
concentration, [S] 		initial reaction
velocity
V0
0.001  26.7 
0.002  45.8 
0.005  80.0 
0.010  106.7 
0.020  128.0 
0.050  145.5 
0.100  152.4 
0.200  156.1 
0.500  158.5 
1.000  159.3 
2.000  159.7 
5.000  159.9 
10.000  160.0 

Using the table (above), calculate the value for the Michaelis-Menten constant, KM.

 

Determining Optimal Enzyme Activity Conditions

Click to show Determining Optimal Enzyme Activity Conditions example problem
Enzyme Effective
Temperature
Range (°C)		 Optimum
pH
A 65–75 10.0 
B 30–48 8.0 
C 15–27 1.0 
D 55–70 5.0 

If enzyme D is currently functioning at 59°C and a pH of 7.0.
Which one of the following conditions would increase the rate of enzyme activity

 

Determining Optimal Enzyme Activity Based on Temperature and pH Conditions

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Enzyme Effective
Temperature
Range (°C)		 Optimum
pH
A 60–72 1.0 
B 50–60 6.0 
C 15–30 3.0 
D 75–85 8.0 

Which one of the enzymes would be most active under the following conditions?
The temperature is 71°C and the pH is 1.2.

 

Determining Optimal Conditions for Enzyme Activity (Temperature and pH)

Click to show Determining Optimal Conditions for Enzyme Activity (Temperature and pH) example problem
Enzyme Effective
Temperature
Range (°C)		 Optimum
pH
A 60–68 3.0 
B 20–30 6.0 
C 40–55 8.0 
D 75–85 10.0 

Under which one of the following conditions would enzyme A be most active?

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