Enzymes · NEET PG Preparation Biochemistry

An enzyme-catalyzed reaction follows standard Michaelis-Menten kinetics. If the substrate concentration is equal to 3 times the Michaelis constant ([…

Practice question from Enzymes (NEET PG Preparation Biochemistry), with the correct answer and a step-by-step solution.

hard · MCQ · Q-00FA47

An enzyme-catalyzed reaction follows standard Michaelis-Menten kinetics. If the substrate concentration is equal to 3 times the Michaelis constant ([S]=3Km[S] = 3K_m), what is the velocity of the reaction (vv) expressed as a fraction of the maximum velocity (VmaxV_{max})?

  1. A.0.25 Vmax
  2. B.0.50 Vmax
  3. C.0.75 VmaxCorrect answer
  4. D.0.90 Vmax

Solution

The Michaelis-Menten equation is v=Vmax[S]Km+[S]v = \frac{V_{max} [S]}{K_m + [S]}. Substituting [S]=3Km[S] = 3K_m gives: v=Vmax(3Km)Km+3Km=3KmVmax4Km=0.75Vmaxv = \frac{V_{max} (3K_m)}{K_m + 3K_m} = \frac{3K_m V_{max}}{4K_m} = 0.75 V_{max}.

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