7: Enzyme Kinetics
Reaction rates, enzyme efficiency, and inhibition mechanisms.
LibreTexts reference: Enzyme Kinetics
Determining Enzyme Inhibition and Activation in Metabolic Pathways
Click to show Determining Enzyme Inhibition and Activation in Metabolic Pathways example problem
A series of enzymes catalyze the reactions in the following metabolic pathway:
| enzyme 1 | enzyme 2 | enzyme 3 | enzyme 4 | |||||||||||||||
| S | ⟶ | T | ⟶ | U | ⟶ | V | ⟶ | W | ||||||||||
Understanding the type of enzyme inhibition or activation is crucial for developing effective drugs and understanding metabolic regulation.
enzyme 1 converts substrate S into product T.The end product W of this pathway binds to enzyme 1at a location far away from its active site.
This binding increases the activity of the enzyme.
Determine the type of enzyme inhibition or activation described:
Identifying Enzyme Catalysis Terminology
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Which one of the following terms related to enzyme catalysis correspond to the definition 'either metallic ions or small organic molecules required for enzyme activity'.
Determining True/False Statements About Enzyme Kinetics
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Which one of the following statements is TRUE of enzyme kinetics?
Determining True/False Statements About Michaelis-Menten Kinetics
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Which one of the following statements is FALSE about Michaelis-Menten kinetics?
Identifying Molecules That Are Not Enzyme Cofactors
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Determining the Michaelis-Menten Constant (Km) from Enzyme Activity Data
Click to show Determining the 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 | 40.0 |
| 0.002 | 60.0 |
| 0.005 | 85.8 |
| 0.010 | 100.0 |
| 0.020 | 109.1 |
| 0.050 | 115.4 |
| 0.100 | 117.7 |
| 0.200 | 118.9 |
| 0.500 | 119.6 |
| 1.000 | 119.8 |
| 10.000 | 120.0 |
Using the table (above), calculate the value for the Michaelis-Menten constant, KM.
Determining Inhibition Type from Enzyme Activity Data
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Michaelis-Menten Kinetics and Inhibition Type Determination
The table below presents data on enzyme activity measured as initial reaction velocities (V0) with and without the presence of an inhibitor at various substrate concentrations ([S]).
| substrate concentration, [S] |
initial reaction velocity no inhibitor V0 (–inh) |
initial reaction velocity with inhibitor V0 (+inh) |
|---|---|---|
| 0.0001 | 9.1 | 6.7 |
| 0.0002 | 16.7 | 11.5 |
| 0.0005 | 33.4 | 20.0 |
| 0.0010 | 50.0 | 26.7 |
| 0.0020 | 66.7 | 32.0 |
| 0.0050 | 83.4 | 36.4 |
| 0.0100 | 91.0 | 38.1 |
| 0.0200 | 95.3 | 39.1 |
| 0.0500 | 98.1 | 39.7 |
| 0.1000 | 99.1 | 39.9 |
| 1.0000 | 100.0 | 40.0 |
Based on the data provided, determine the type of inhibition show by the inhibitor. Consider how the addition of the inhibitor affects the initial reaction velocities (V0) at various substrate concentrations ([S]).
Identifying Molecules That Could Be Enzymes
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Enzymes are biological catalysts that speed up chemical reactions in living organisms.
Which one of the following choices is most likely an enzyme?
Hint: enzymes often have a distinct naming pattern that can help identify them.