Question

Michaelis constant biomolecules____.

• A. The rate of enzymatic activity
• B. The rate of reaction
• C. Substrate concentration at which the rate of reaction is maximum
• D. Substrate concentration at which the reaction attains half of its maximum velocity

Answer 1

The correct option is D

Substrate concentration at which the reaction attains half of its maximum velocity

The correct option is D.
Explanation of the correct option:

1. The Michaelis constant (K_M), defined as the concentration of substrate transported at half the maximal velocity (Vmax), is a measure of the transporter's affinity for its substrate.
2. K_m is the Michaelis-Menten constant, which indicates the concentration of the substrate when the reaction velocity is half of the maximum velocity for the reaction.
3. It can also be viewed as a measure of how well a substrate interacts with a specific enzyme, also known as binding affinity.
4. The k_m varies from enzyme to enzyme and is used to classify the enzymes.
5. A lower k_m value suggests a stronger affinity of the enzyme for its substrate and, as a result, a faster reaction.
6. The enzyme interacts with the substrate to produce an enzyme-substrate complex, which results in product production and enzyme release:
   $v=\frac{V_{max}\left[S\right]}{K_m+\left[S\right]}$ Where,

	=	velocity of reaction
	=	maximum rate achieved by the system
	=	concentration of a substrate S
	=	Michaelis constant

Explanation of the incorrect options:
Option A:

1. The amount of substrate converted to the product over time is used to calculate an enzyme's rate of reaction.
2. Substrates and product amounts are frequently referred to in molar concentrations, or moles of substance per volume when discussing rates.

Option B:

1. Reaction rates are often stated as the amount of reactant consumed or the amount of product created per unit time.
2. Thus, the units are moles per liter per unit time, denoted as M/s, M/min, or M/h.
3. Chemists measure reaction rates by starting the reaction, measuring the concentration of the reactant or product at different periods as the reaction occurs, sometimes plotting the concentration as a function of time on a graph, and then calculating the change in concentration per unit time.

Option C:

This indicates that any small change in substrate concentration will alter the reaction rate proportionally (for instance, if the substrate concentration increases, then the reaction rate will also increase, assuming that enzyme concentration is held constant).

Final answer: Michaelis constant biomolecules substrate concentration at which the reaction attains half of its maximum velocity.