Multiple Choice
Because of the _____________ substrate-binding-site(s) & conformation(s) on an allosteric enzyme, the range of [S] to reach the Vmax is _______________ for allosteric enzymes than it is for Michaelis-Menten enzymes.
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7. Enzyme Inhibition and Regulation
Allosteric Kinetics
Multiple Choice
Which of the following statements regarding allosteric kinetics is false?
A
The rate of an allosteric enzyme reaction is dependent on substrate concentration [S].
B
The reaction velocity and substrate concentration always proportionally change in a Lineweaver-Burk plot.
C
At saturating [S], the kinetics of an allosteric enzyme will follow the Michaelis-Menten model.
D
Allosteric enzymes display second order kinetics leading to sigmoidal curvature on a kinetics plot.
E
None are false because all of the above are true.
Verified step by step guidance1
Understand the concept of allosteric enzymes: Allosteric enzymes are those whose activity is modulated by the binding of an effector molecule at a site other than the enzyme's active site. This can result in changes to the enzyme's activity and kinetics.
Review the Lineweaver-Burk plot: This is a double reciprocal plot used to illustrate the kinetics of enzyme-catalyzed reactions. For Michaelis-Menten kinetics, this plot is linear, but allosteric enzymes often do not follow this linear relationship due to their cooperative binding.
Examine the statement about reaction velocity and substrate concentration: In allosteric enzymes, the relationship between reaction velocity and substrate concentration is not always proportional, especially in a Lineweaver-Burk plot, due to the sigmoidal nature of their kinetics.
Consider the statement about Michaelis-Menten kinetics at saturating [S]: At high substrate concentrations, some allosteric enzymes can exhibit Michaelis-Menten-like kinetics, where the reaction rate becomes independent of substrate concentration.
Evaluate the statement about second order kinetics and sigmoidal curvature: Allosteric enzymes often display sigmoidal kinetics due to cooperative binding, which is a hallmark of second order kinetics, leading to a characteristic S-shaped curve on a kinetics plot.
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