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7: Enzyme Kinetics

Reaction rates, enzyme efficiency, and inhibition mechanisms.

Enzyme Inhibition and Activation in Metabolic Pathways

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A series of enzymes catalyze the reactions in the following metabolic pathway:

enzyme 1 enzyme 2 enzyme 3 enzyme 4
B  ⟶  C  ⟶  D  ⟶  E  ⟶  F
                                     

Understanding the type of enzyme inhibition or activation is crucial for developing effective drugs and understanding metabolic regulation.

enzyme 1 converts substrate B into product C.

The end product F of this pathway binds to enzyme 1in its active site blocking the substrate.
This binding decreases the activity of the enzyme.
Determine the type of enzyme inhibition or activation described:

 

Enzyme Catalysis Terminology

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Which one of the following terms related to enzyme catalysis correspond to the definition 'substance used to cause or facilitate a chemical reaction'.

 

True/False Statements on Enzyme Kinetics

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Which one of the following statements is TRUE about enzyme kinetics?

 

True/False Statements on Michaelis-Menten Kinetics

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Which one of the following statements is TRUE of Michaelis-Menten kinetics?

 

Which Molecule Cannot be an Enzyme Cofactors

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Which one of the following molecular entities CANNOT be classified as an enzymatic cofactor?
 

Michaelis-Menten Constant (KM) from Enzyme Activity Data

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

substrate
concentration, [S]
initial reaction
velocity
V0
0.0001  9.6 
0.0002  18.2 
0.0005  40.0 
0.0010  66.7 
0.0020  100.0 
0.0050  142.9 
0.0100  166.7 
0.0200  181.9 
0.0500  192.4 
0.1000  196.1 
1.0000  199.7 
10.0000  200.0 

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

 

Inhibition Type Determination 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  13.4  6.7 
0.0002  22.9  11.5 
0.0005  40.0  20.0 
0.0010  53.4  26.7 
0.0020  64.0  32.0 
0.0050  72.8  36.4 
0.0100  76.2  38.1 
0.0200  78.1  39.1 
0.0500  79.3  39.7 
0.1000  79.7  39.9 
1.0000  80.0  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]).

 

Which Molecule Could be an Enzyme

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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.