(DEC 2001)
64. False statement of competitive inhibition is-
(1) Structure same as substrate
(2) Inhibits substrate binding
(3) Binds to active site
(4) Reaction cannot be favorably biased by increasing substrate concentration
The correct answer is (4) Reaction cannot be favorably biased by increasing substrate concentration.
Introduction
Competitive inhibition is a classic and vital concept in enzyme kinetics and drug design. It involves inhibitors that structurally mimic the substrate, binding at the enzyme’s active site and thereby blocking substrate access. A critical point often misunderstood is whether increasing substrate concentration can reverse this inhibition. Understanding this principle is essential for interpreting enzyme behavior and pharmacological interventions accurately.
Characteristics of Competitive Inhibition
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Structure similarity:
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Competitive inhibitors usually resemble the substrate, enabling them to bind the enzyme’s active site.
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Inhibiting substrate binding:
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By occupying the active site, the inhibitor prevents substrate molecules from binding.
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Binds to active site:
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Direct competition at the substrate’s binding location is essential for competitive inhibition.
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Substrate concentration effect:
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Increasing substrate concentration can overcome competitive inhibition by outcompeting the inhibitor for the active site.
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Therefore, the reaction rate can be favorably biased by adding more substrate.
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Why Statement (4) is False
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The defining feature of competitive inhibition is that it can be reversed by increasing substrate levels.
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If the substrate concentration exceeds inhibitor concentration, substrate binding predominates, restoring enzyme activity.
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This contrasts with non-competitive inhibition, where substrate concentration does not affect inhibition.
Summary Table
| Statement | Truth Value | Explanation |
|---|---|---|
| (1) Structure same as substrate | True | Enables binding to active site |
| (2) Inhibits substrate binding | True | Competes for active site |
| (3) Binds to active site | True | Definitive mechanism of competitive inhibition |
| (4) Reaction cannot be favored by substrate increase | False | Increasing substrate overcomes inhibition |
Biological and Pharmaceutical Relevance
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Many drugs act as competitive inhibitors (e.g., methotrexate).
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Rational modulation of substrate concentration can influence enzyme activity and drug efficacy.
Conclusion
The incorrect statement about competitive inhibition is that increasing substrate concentration cannot bias the reaction favorably. In reality, competitive inhibition is uniquely reversible by substrate concentration, marking statement (4) as false.
35 Comments
Kirti Agarwal
September 12, 2025Reaction can not be favorably biased by increasing substrate conc.
Khushi Vaishnav
September 12, 2025Reaction cannot be favorably biased by increasing substrate concentration.
Kajal
September 12, 2025Option 4is correct as we can overcome the competitive inhibition by increasing the concentration of substrate
Bharti yadav
September 13, 2025Reaction cannot be favorably biased by increasing substrate concentration.
yashika
September 13, 2025Competitive us all about increasing cocentration
Kanica Sunwalka
September 13, 2025in competitive inhibition ,
rxn can be reversed by increasing substrate conc.
so , option 4 is incorrect
Aakansha sharma Sharma
September 13, 2025The correct answer is (4) Reaction cannot be favorably biased by increasing substrate concentration.
Rishita
September 14, 2025Option 4
Pratibha Jain
September 14, 2025correct answer is option (4)
Reaction cannot be favorably biased by increasing substrate concentration.
Santosh Saini
September 14, 2025Reaction cannot be favored by increasing the concentration of substrate
Aartii sharma
September 14, 2025Reaction cannot be favoured by increasing the substrate concentration
Dharmpal Swami
September 14, 2025Rex.cannot be favoured by increasing the substrate concentration
anjani sharma
September 14, 2025Answer 4
Increasing substrate overcomes inhibition
Konika Naval
September 14, 2025Reaction can not be favourably biased by increasing substrate concentration
Pallavi Ghangas
September 14, 2025Competitive inhibition can be overcome by increasing the substrate concentration
Palak Sharma
September 14, 2025Increasing substrate overcomes inhibition.
Sakshi yadav
September 14, 2025reaction cannot be favorably biased by increasing substrate concentration.
Ankita Pareek
September 14, 2025Option 4th is incorrect because in compititive inhibition reaction can be reversed by increasing the substrate concentration,as the substrate concentration exceeds the inhibitor concentration, substrate binding predominates restoring enzymes activity
Priya dhakad
September 14, 2025Reaction can not be favourably biased by increasing substrate concentration.
Sakshi Kanwar
September 14, 2025As competitive inhibition involves the inhibitor ha same structure as substrate it also inhibits substrate binding and Binds to active site
So option4 is incorrect
Soniya Shekhawat
September 15, 2025If the substrate concentration exceeds inhibitor concentration, substrate binding predominates, restoring enzyme activity.
This contrasts with non-competitive inhibition, where substrate concentration does not affect inhibition.
Aafreen Khan
September 15, 2025Reaction cannot be favorably biased by increasing substrate concentration
Vanshika Sharma
September 15, 2025Reaction cannot be favourable biased by increasing substrate concentration
Mohd juber Ali
September 15, 2025Inhibitor inhibit binding of substrate at active site of enzyme and prevent formation of product and inhibitor structure same as substrate option 4 is false
Nilofar Khan
September 16, 2025correct answer is (4) Reaction cannot be favorably biased by increasing substrate concentration.
Payal Gaur
September 16, 2025Options 4 . Reaction can not be favorably biased by increasing substrate concentration because in competitive substrate bind with enzyme (increase substrate concentration) and decrease binding of inhibitor.
Tanvi Panwar
September 16, 2025Reaction cannot be favourably biased by increasing substrate concentration is incorrect statement bcz at infinite substrate concentration Vmax. is maximum.
Khushi Agarwal
September 17, 2025Correct Answer:(4)
Reaction cannot be favorably biased by increasing substrate concentration
Competitive inhibition me agar zyada substrate daalenge to inhibitor ko side kar doge reaction phir normal speed se chalega.
Simran Saini
September 17, 2025Reaction cannot be favorably biased by increasing substrate concentration.
Lokesh Kumawat
September 17, 2025Reaction cannot be favorably biased by increasing substrate concentration.
Priti khandal
September 17, 20254th is false done sir
Avni
September 17, 2025The correct answer is (4) Reaction cannot be favorably biased by increasing substrate concentration.
Minal Sethi
September 19, 2025reaction cannot be favorably biased by increasing substrate concentration.
Muskan Yadav
September 19, 2025Reaction cannot be favorably biased by increasing substrate concentration.
Kajal
September 25, 2025The correct answer is (4) Reaction cannot be favorably biased by increasing substrate concentration