wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

The figure given below show three velocity – substrate concentration curves for an enzyme reaction.
What do the curves a, b and c depict respectively?

A
a - normal enzyme reaction, b - competitive
inhibition, c - non-competitive inhibition
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
a - enzyme with an allosteric modulator added, b - normal enzyme activity, c - competitive inhibition.
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
a - enzyme with an allosteric stimulator, b - competitive inhibitor added, c - normal enzyme reaction
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
a - normal enzyme reaction, b - non-competitive inhibitor added, c - allostric inhibitor added.
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

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.


flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Enzymes
BIOLOGY
Watch in App
Join BYJU'S Learning Program
CrossIcon