![(FEB 2022-1) 25. The following statements are being made to define the Michaelis constant (KM). It is: A. Independent of enzyme concentration [E] and substrate concentration [S] B. Equal to the dissociation constant when the [ES] complex dissociates more rapidly than product formation C. Equal to the dissociation constant when product formation is more rapid than [ES] complex dissociation D. An intrinsic property of an enzyme and does not depend on pH, temperature and ionic strength Which one of the following combination of statements is correct? (1) A and B only (2) A, B and D only (3) C and D only (4) A and D only](https://www.letstalkacademy.com/wp-content/uploads/2025/09/25.jpg)
(FEB 2022-1)
25. The following statements are being made to define the Michaelis constant (KM). It is:
A. Independent of enzyme concentration [E] and substrate concentration [S]
B. Equal to the dissociation constant when the [ES] complex dissociates more rapidly than
product formation
C. Equal to the dissociation constant when product formation is more rapid than [ES] complex dissociation
D. An intrinsic property of an enzyme and does not depend on pH, temperature and ionic strength
Which one of the following combination of statements is correct?
(1) A and B only (2) A, B and D only
(3) C and D only (4) A and D only
The correct answer is (1) A and B only.
Introduction
The Michaelis constant (Km) is a pivotal parameter in enzyme kinetics, indicating the substrate concentration at which the reaction rate is half of its maximum velocity (Vmax). Its precise definition and properties have important implications for enzyme function, substrate affinity, and reaction dynamics. This article evaluates statements about Km’s characteristics, focusing on its independence from enzyme/substrate concentration and when Km can be equated to the dissociation constant of the enzyme-substrate (ES) complex.
Statement Analysis
A. Km is independent of enzyme concentration [E] and substrate concentration [S]
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Correct.
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Km is an intrinsic kinetic constant for a given enzyme-substrate pair under specific conditions.
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It remains constant regardless of enzyme or substrate concentration changes.
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It reflects enzyme affinity for substrate and catalytic capability.
B. Km equals the dissociation constant when the ES complex dissociates more rapidly than product formation.
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Correct.
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When the rate constant for ES complex breakdown to enzyme + substrate k−1 is much greater than the catalytic rate constant kcat, Km approaches the equilibrium dissociation constant Kd=k−1/k1.
C. Km equals the dissociation constant when product formation is more rapid than ES complex dissociation.
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Incorrect.
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If product formation kcat is faster than ES dissociation k−1, Km does not equal Kd and is more complicated.
D. Km is an intrinsic property of enzyme and does not depend on pH, temperature, and ionic strength.
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Incorrect.
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Km depends on experimental conditions including pH, temperature, and ionic strength, which affect enzyme and substrate interactions.
Fundamentals of Michaelis Constant
Km=k−1+kcatk1
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k1: rate constant substrate binds enzyme.
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k−1: rate constant substrate dissociates.
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kcat: catalytic conversion rate.
Implications of Km Values
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Km describes how tightly enzyme binds substrate.
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Smaller Km means higher affinity.
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Conditions altering enzyme conformation affect Km.
Summary Table
| Statement | Correct/Incorrect | Reason |
|---|---|---|
| A. Km independent of [E] and [S] | Correct | Km is intrinsic for enzyme-substrate pair |
| B. Km equals Kd if k−1≫kcat | Correct | When ES dissociation dominates, Km = Kd |
| C. Km equals Kd if kcat>k−1 | Incorrect | Km no longer equals simple Kd |
| D. Km does not depend on pH, temperature, ionic strength | Incorrect | Experimental conditions affect Km |
Conclusion
Statements A and B correctly describe Michaelis constant properties. Km is independent of enzyme and substrate concentration and equals the dissociation constant of the ES complex only if the complex dissociates faster than product formation. Km varies with environmental factors, making statements C and D false. Understanding this helps interpret enzyme kinetics and design biochemical experiments accurately.
40 Comments
Aakansha sharma Sharma
September 12, 2025Statements A and B correctly describe Michaelis constant properties. Km is independent of enzyme and substrate concentration and equals the dissociation constant of the ES complex only if the complex dissociates faster than product formation.
Varsha Tatla
September 12, 2025A,B is correct
Priya dhakad
September 12, 2025Km is independent of enzyme and substrate concentration and equals the dissociation constant of the ES complex only if the complex dissociates faster than product formation.
Sakshi yadav
September 13, 2025A. Independent of [E] and [S] conc.
B. Equal to the dissociation constant when the [ES] complex dissociates more rapidly than product formation
Khushi Vaishnav
September 13, 2025A and B are correct statement
Bhawna Choudhary
September 13, 2025A and B is the correct answer
Mohd juber Ali
September 14, 2025Km = k(dissociation)
rb1=km =k(dissociation)
Es complex ka E + s me dissociation jyada hoga product formation kam hoga (option B )
Option1 km is internsic constant for (independent )enzyme and substrate pair
Aafreen Khan
September 14, 2025A and B is the correct answer
Soniya Shekhawat
September 14, 2025Km is be independent on enzyme and substrate concentration and Equal to the dissociation constant when the [ES] complex dissociates more rapidly than
product formation.
Pooja
September 14, 2025A and B statement is correct
Dharmpal Swami
September 14, 2025Km is independent on enzyme and substrate construction
ES complex dissociation more rapidly than product formation
Kirti Agarwal
September 14, 2025Correct answer is A and B
Payal Gaur
September 14, 2025A and B is correct dissociation of ES complex in E+ S rapidly then product formation . Km is the independent constant for Enzyme and substrate construction.
Tanvi Panwar
September 14, 2025A and B are correct statements as Km is independent of enzymes and substrate concentration and equal to dissociation constant when dissociation of ES is more Than product formation.
Kajal
September 14, 2025Statement A and B are correct
Anurag Giri
September 14, 2025Statements A and B correctly describe Michaelis constant properties. Km is independent of enzyme and substrate concentration and equals the dissociation constant of the ES complex only if the complex dissociates faster than product formation
Kanica Sunwalka
September 14, 2025A and B are correct statements
Neha Yadav
September 14, 2025Km is independent on enzyme and substrate concentration
Equal to the dissociation constant when the [ES] complex dissociates more rapidly than product formation ( km = kd )
Anju
September 14, 2025Ans : A&B
Km dependent of E&S and equal to kdi of ES complex if ES dissociation faster than product formation
Anjali
September 14, 2025Statement A and B are correct
Avni
September 14, 20251. Independent of enzyme concentration [E] and substrate concentration [S]
2. Equal to the dissociation constant when the [ES] complex dissociates more rapidly than
product formation
HIMANI FAUJDAR
September 14, 2025Ans A and B is correctly described the Michaelis constant properties in which Km is independent of enzyme and substrate concentration and equals the dissociation constant of the ES complex only if the complex dissociates faster. than product formation.
Santosh Saini
September 14, 2025Km is independent of enzyme and substrate concentration and equal the Kd of the ES complex only if the complex dissociate faster than product formation
anjani sharma
September 14, 2025Statement A and B are correct
Pallavi Ghangas
September 14, 2025A and b
Heena Mahlawat
September 14, 2025Km is independent of substrate concentration and enzyme concentration as it remains constant regardless of enzyme or substrate concentration changes and reflects enzyme affinity for substrate
And km equals dissociation constant when ES complex dissociates more rapidly than product formation
Nilofar Khan
September 15, 2025Correct answer is And B
Mitali saini
September 15, 2025The correct answer is (1) A and B only.
Khushi Agarwal
September 15, 2025KM is
A. Independent of enzyme concentration [E] and substrate concentration [S]
B. Equal to the dissociation constant when the [ES] complex dissociates more rapidly than product formation
Bcz Km enzyme/substrate concentration pe depend nahi karta, aur jab ES wapas E+S banne me fast ho (product banane se tez), tab Km ≈ dissociation constant
Asha Gurzzar
September 15, 2025A and b are correct statement
Muskan singodiya
September 15, 2025A and b is correct
Independent of enzyme con. ES and subtrate con. S
Equal dissociation constant when ES complex dissociates more rapidly than product formation
Simran Saini
September 15, 2025A and B only
Independent of enzyme concentration [E] and substrate concentration [S]
Equal to the dissociation constant when the [ES] complex dissociates more rapidly than
product formation
Arushi Saini
September 15, 2025Statement A and B is correct
Km is independent of enzymes and substrate concentration and equal to dissociation constant when dissociation of ES is more Than product formation.
Anjana sharma
September 16, 2025Option a and b is correct
Sonal nagar
September 16, 2025Option 1
(A and B)
Minal Sethi
September 16, 2025independent of [E] and [S] concentration and it is equal to dissociation constant when dissociation of ES is more than product formation
Palak Sharma
September 16, 2025A. Independent of [E] and [S] conc.
B. Equal to the dissociation constant when the [ES] complex dissociates more rapidly than product formation
Muskan Yadav
September 17, 2025Independent of enzyme concentration [E] and substrate concentration [S] AND Equal to the dissociation constant when the [ES] complex dissociates more rapidly than product formation . A and B is the correct answer.
Deepika sheoran
September 18, 2025Option A &B
Enzyme concentration (E) & Substrate concentration (S)
Complex dissociation more rapidly than product formation.
Khushi Singh
September 25, 2025A and B is correct