Question:
Km value is defined as?
Km value is defined as?
Show Hint
Set v = Vmax/2 in the Michaelis-Menten equation and Km equals that substrate concentration.
Updated On: Jun 24, 2026
- Substrate concentration at Vmax/2
- Substrate concentration of twice Vmax
- Substrate concentration of thrice Vmax
- Substrate concentration of one third Vmax
Show Solution
Verified By Collegedunia
The Correct Option is A
Solution and Explanation
Step 1: Km is the Michaelis constant from Michaelis-Menten enzyme kinetics, described by the equation \(v = \dfrac{V_{max}[S]}{K_m + [S]}\).
Step 2: By definition, Km is the substrate concentration at which the reaction velocity is half of the maximum, that is when \(v = V_{max}/2\). Substituting this into the equation gives \(K_m = [S]\) at that point.
Step 3: Km is therefore an indicator of enzyme affinity: a low Km means high affinity for the substrate, and a high Km means low affinity. The other options describe "twice", "thrice" or "one third" of Vmax, which have no kinetic definition and are simply incorrect.
Step 4: Hence Km is the substrate concentration at half-maximal velocity, Vmax/2, option (a).
Step 2: By definition, Km is the substrate concentration at which the reaction velocity is half of the maximum, that is when \(v = V_{max}/2\). Substituting this into the equation gives \(K_m = [S]\) at that point.
Step 3: Km is therefore an indicator of enzyme affinity: a low Km means high affinity for the substrate, and a high Km means low affinity. The other options describe "twice", "thrice" or "one third" of Vmax, which have no kinetic definition and are simply incorrect.
Step 4: Hence Km is the substrate concentration at half-maximal velocity, Vmax/2, option (a).
Was this answer helpful?
0
0
Top NEET PG Biochemistry Questions
- Which of the following clotting factors is needed for gamma-glutamyl carboxylase?
- A patient presented with diarrhea, dermatitis, and dementia. Which of the following vitamin deficiencies would you suspect in this patient?
- A young boy presents to the OPD with hypoglycemia and muscle cramps, on exertion or while playing. Then he becomes normal after resting for a while. These episodes are recurrent after a period of activity. He has decreased serum lactate and glucose levels. Which of the following diseases is he most likely to be suffering from?
- A family consumes only polished rice. Which of the following combinations of vitamin deficiency and enzymatic defect will be present in this family?
- A chronic alcoholic patient presented to the casualty with confusion, ataxia, and painful eye movements. What could be the vitamin deficiency seen in this patient?
View More Questions
Top NEET PG Questions
- A patient hailing from Delhi presents with fever, arthralgia, and extensive petechial rash for 3 days. Lab investigations revealed a hemoglobin of 9 g/ dL, a white blood cell count of 9000 cells/mm3, a platelet count of 20000 cells/mm3, and a prolonged bleeding time. The clotting time was normal. What is the most likely diagnosis?
- Which of the following statements is true about Trichomonas vaginalis?
- A lady from West Rajasthan presented with an ulcer surrounded by erythema on the right leg. Microscopy of the biopsy from the edge of the ulcer showed organisms with dark staining nuclei and kinetoplast. What is the most likely causative agent?
- A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?
- Infection with Clonorchis sinensis is associated with an increased risk of__?
View More Questions