Chemistry GS TIFR- Tata Institute of Fundamental Research Questions 11_ Solved
11. The Michaelis-Menten equation can be represented as follows:
v = Vmax.
For an intracellular enzyme to function optimally, which of the following statements regarding intracellular substrate concentration is true?
(i) The intracellular substrate concentration should be greater than the Km of the enzyme.
(ii) The intracellular substrate concentration should be significantly lower than the Km of the enzyme.
(iii) The intracellular substrate concentration is independent of the Michaelis constant Km.
(iv) The intracellular substrate concentration should be approximately the same as that of the Km.
Answer: The Michaelis-Menten equation relates the rate of an enzymatic reaction (v) to the concentration of substrate ([S]) and two constants, the maximum reaction rate (Vmax) and the Michaelis constant (Km):
v = (Vmax [S]) / (Km + [S])
For an intracellular enzyme to function optimally, the intracellular substrate concentration should be high enough to saturate the enzyme's active sites. At saturation, all enzyme molecules are bound to the substrate, and the reaction rate is maximal (i.e., equal to Vmax).
However, it's important to note that the exact concentration required to saturate the enzyme will depend on the specific enzyme and the particular conditions of the cell or tissue. This concentration can be estimated by determining the Km value for the enzyme, which is the substrate concentration required to achieve a half-maximal reaction rate.
Therefore, the optimal intracellular substrate concentration for an enzyme can be described as a concentration that is high enough to saturate the enzyme's active sites but not so high that the enzyme becomes inhibited or overwhelmed by excess substrate.