Kinetics of Enzyme Inhibition

1. •Inhibitor- Any agent that decreases the velocity
of an enzyme catalyzed reaction.
•Inhibition may be of reversible or non-
reversible type.
1.Competitive Inhibitors- They compete directly
with the substrate for the active site of the
enzyme.
•This inhibition can be tackled by the addition of
more substrate.
Competitive inhibition
Kinetics of Enzyme Inhibition

2. 2. Uncompetitive
Inhibitors-
•These bind only to the Enzyme-Substrate complex, as
binding of a substrate to enzyme creates a binding site for
inhibitor.
•In this case Vmax and Km​ decreases .
Kinetics of Enzyme Inhibition-

3. Non-Competitive Inhibitors
•It can combine either with free substrate or the ES
complex.
•They bind to a site other than active site of the enzyme.
•In this case Vmax decreases and Km​ remains unchanged.
Kinetics of Enzyme Inhibition-

4. •The allosteric enzymes have another site called allosteric
site.
•Some molecule binding to allosteric site can act either as
activator or inhibitor.
•They do not follow Michaelis-Menten kinetics instead of
hyperbolic curve they show a sigmoidal curve because a
small change in concentration will bring about a large
change in reaction rate.
Kinetics of Allosteric enzymes-

5. Significance of enzyme kinetics
• With the help of enzyme kinetics we can determine the rate of the reaction with the
changes in substrate concentration as well as we can determine the effect of inhibitors on
reaction rate.
• It helps us to explain how enzyme works.
• Helps us to determine how drugs and poisons inhibit the enzyme activity.
• Helps us to understand enzyme's role in metabolic pathway.
• It helps us to predict how enzymes behave in living organisms.