Multiple Choice
Michaelis & Menten assumed that the initial reaction for an enzyme catalyzed reaction could be written as shown:
Using this, the rate/velocity of ES-complex breakdown can be expressed by:
6. Enzymes and Enzyme Kinetics
Michaelis-Menten Assumptions
Multiple Choice
Which of the following options is not an assumption made in deriving the Michaelis-Menten equation?
A
The value of k-2 can be ignored.
B
The rate of ES formation = to rate of P formation.
C
The [E] is smaller than the [S].
D
a, b & c are all correct assumptions.
Verified step by step guidance1
Understand the Michaelis-Menten equation: It describes the rate of enzymatic reactions by relating reaction rate to substrate concentration, enzyme concentration, and two constants (Km and Vmax).
Identify the assumptions made in deriving the Michaelis-Menten equation: These include the steady-state assumption, where the formation and breakdown of the enzyme-substrate complex (ES) are balanced, and the assumption that the reverse reaction from product to substrate is negligible (k-2 is ignored).
Analyze the given options: The statement 'The rate of ES formation = to rate of P formation' is not a correct assumption. Instead, the rate of ES formation is equal to the rate of ES breakdown (to form product and revert to enzyme and substrate).
Consider the assumption '[E] is smaller than [S]': This is a valid assumption in the Michaelis-Menten model, as it allows the simplification that substrate concentration remains approximately constant during the reaction.
Conclude that the correct answer is the statement that does not align with the assumptions of the Michaelis-Menten equation, which is 'The rate of ES formation = to rate of P formation.'
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