The figure given below show three velocity – substrate concentration curves for an enzyme reaction.
What do the curves a, b and c depict respectively?
The figure given below show three velocity – substrate concentration curves for an enzyme reaction.
What do the curves a, b and c depict respectively?
The correct option is A a - normal enzyme reaction, b - competitive
inhibition, c - non-competitive inhibition
The curve a represents the normal enzyme catalysed reaction with no inhibitor. Inhibition can reduce the reaction rate of enzymes.
Competitive and non competitive inhibition affect the rate of reaction differently.
Competitive inhibitors affect the initial rate, but do not affect the maximal rate (curve b), whereas non competitive inhibitors affect the maximal rate (Curve c).
A competitive inhibitor is any compound which closely resembles the chemical structure and molecular geometry of the substrate. The inhibitor competes for the same active site as the substrate molecule. The inhibitor may interact with the enzyme at the active site, but no reaction takes place. The inhibitor is "stuck" on the enzyme and prevents any substrate molecules from reacting with the enzyme. However, a competitive inhibition is usually reversible if sufficient substrate molecules are available to ultimately displace the inhibitor. Therefore, the amount of enzyme inhibition depends upon the inhibitor concentration, substrate concentration, and the relative affinities of the inhibitor and substrate for the active site. Noncompetitive inhibition of an enzyme can occur when an inhibitor binds to an enzyme at a site other than the active site. The noncompetitive inhibitor slows down the reaction rate, i.e. the rate of the product formation is less with inhibitor present than with inhibitor absent. This means that the active site is modified, but not disabled, by the presence of the inhibitor.
As shown in curve C the effect of noncompetitive inhibitor cannot be overcome with high substrate concentration. Since the inhibitor and substrate are not competing for the same binding site on the enzyme, a noncompetitive inhibitor reduces the reaction rate at all substrate concentrations.
inhibition, c - non-competitive inhibition
The curve a represents the normal enzyme catalysed reaction with no inhibitor. Inhibition can reduce the reaction rate of enzymes.
Competitive and non competitive inhibition affect the rate of reaction differently.
Competitive inhibitors affect the initial rate, but do not affect the maximal rate (curve b), whereas non competitive inhibitors affect the maximal rate (Curve c).
A competitive inhibitor is any compound which closely resembles the chemical structure and molecular geometry of the substrate. The inhibitor competes for the same active site as the substrate molecule. The inhibitor may interact with the enzyme at the active site, but no reaction takes place. The inhibitor is "stuck" on the enzyme and prevents any substrate molecules from reacting with the enzyme. However, a competitive inhibition is usually reversible if sufficient substrate molecules are available to ultimately displace the inhibitor. Therefore, the amount of enzyme inhibition depends upon the inhibitor concentration, substrate concentration, and the relative affinities of the inhibitor and substrate for the active site.
Noncompetitive inhibition of an enzyme can occur when an inhibitor binds to an enzyme at a site other than the active site. The noncompetitive inhibitor slows down the reaction rate, i.e. the rate of the product formation is less with inhibitor present than with inhibitor absent. This means that the active site is modified, but not disabled, by the presence of the inhibitor.
As shown in curve C the effect of noncompetitive inhibitor cannot be overcome with high substrate concentration. Since the inhibitor and substrate are not competing for the same binding site on the enzyme, a noncompetitive inhibitor reduces the reaction rate at all substrate concentrations.
