Question

Michaelis Menten Constant $({K_m})$ Is equal to
a. The rate of reaction
b. The rate of enzymatic activity
c. Substrate concentration at which the reaction attains half of its maximum velocity
d. Substrate concentration at which the rate of reaction is maximum

Answer 1

Hint: One of the best-known models of enzyme kinetics is Michaelis-Menten kinetics. This model is named after Leonor Michaelis (german biochemist) and Maud Menten (physician). It helps to measure the efficiency of the enzyme to convert the substrate into a product.

Complete answer:
The substance concentration which is expressed in moles/l at which half of the maximum velocity in enzyme-catalyzed molecules are bound with substrate molecules when the concentration of substrate is equal to the value of ${K_m}$ and is called the Michaelis-Menten constant. It is referred to as a characteristic feature for any given enzyme. It measures the ES complex strength.

A strong affinity between enzyme and substrate indicates the low value of ${K_m}$. The weal affinity between enzyme and substrate indicates a high value of ${K_m}$. The ${K_m}$ value for most of the enzymes is between 10-5 to 10-2 moles.

Hence, the correct answer is option (C).

Additional information:
There are different biochemical situations in which the Michaelis-Menten Model can be used apart from the enzyme-substrate reaction. For example – antigen-antibody binding, DNA-DNA hybridization, and protein-protein interaction. The generic biochemical reaction is also characterized by this model.

${K_m}$ value is dependent on the identity of the enzyme and substrate both. Also, temperature and pH conditions are the factor of ${K_m}$ on which it depends. The purity or concentration of the enzyme does not affect the ${K_m}$ constant.
The Monod equation is in the form of an empirical equation that can be applied for microbial growth.

Note: Thus, Michaelis-Menten constant or ${K_m}$ tell us about the substrate concentration when the velocity of the reaction is equal to half of the maximal reaction velocity. The equation of the Michaelis-Menten constant is ${v_0} = \dfrac{v_{\max } \times [S]}{({K_m} + [S])}$ where ${v_{\max }}$shows how fast an enzymatic reaction is and $[S]$ shows the concentration of the substrate.