Experiment 5: Michaelis-Menten Kinetics and Enzyme Inhibition Flashcards
What does it mean for an enzyme to be saturated?
if the active site of the enzyme is continuously occupied by a molecule, whether that is a substrate, product, or an intermediate molecule. this happens at very high substrate concentrations.
What is Vmax? How can it be calculated?
Vmax is an asymptote, and is the catalytic rate when the enzyme is saturated with substrate.
Vmax is just the -ve reciprocal y intercept.
What does a Michaelis-Menten plot depict?
The relationship between V0 (initial rate) and [S].
What does the levelling off portion in a reaction progress curve mean? and what does it mean in a Michaelis-Menten graph?
The levelling off portion in a reaction progress is because equilibrium has been reached. Comparatively, in a Michaelis-Menten graph, the levelling off portion means that the enzyme has been saturated.
What is the Michaelis-Menten constant (Km)? How can it be calculated from a graph?
The Michaelis-Menten constant has units of concentration and is a composite of several rate constants over the catalytic cycle.
Km is just the -ve reciprocal of the x intercept.
What is competitive inhibition? What happens to Vmax and Km?
inhibitors that bind in the ACTIVE SITE of the enzyme, and therefore compete with the normal substrate for binding to the enzyme, are known as competitive inhibitors.
Unchanging Vmax, but increasing Km with increasing inhibitor [ ] are the defining characteristics of competitive inhibition.
What is non-competitive inhibition? What happens to Vmax and Km?
Inhibitors that bind to an enzyme at a site that is NOT the active site and bind independently of the presence or absence of bound substrate, are known as non-competitive inhibitors.
As the [ ] of inhibitor is increased, the Vmax gets lower, and Km appears unchanged.
What is an uncompetitive inhibitor?
Inhibitors that can only bind to the enzyme AFTER a substrate is bound are known as uncompetitive inhibitors.
