1. What is Michaelis Constant?

Definition: The Michaelis Constant (K_M) is numerically equal to the substrate concentration at which the reaction rate is half of the maximum rate of the system.

Purpose: It's a key parameter in enzyme kinetics that indicates the affinity of an enzyme for its substrate.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( K_M \) — Michaelis Constant (M)
• \( k_r \) — Reverse rate constant (M/s)
• \( k_{cat} \) — Catalytic rate constant (1/s)
• \( k_f \) — Forward rate constant (1/s)

Explanation: The sum of the reverse and catalytic rate constants is divided by the forward rate constant to determine the Michaelis Constant.

3. Importance of Michaelis Constant

Details: K_M is crucial for understanding enzyme efficiency and substrate binding. Lower K_M values indicate higher enzyme-substrate affinity.

4. Using the Calculator

Tips: Enter the reverse rate constant (k_r) in M/s, catalytic rate constant (k_cat) in 1/s, and forward rate constant (k_f) in 1/s. The forward rate constant must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What does a high Michaelis Constant indicate?
A: A high K_M suggests low enzyme-substrate affinity, meaning more substrate is needed to reach half of V_max.

Q2: How is K_M related to enzyme efficiency?
A: While K_M measures substrate binding affinity, k_cat/K_M is a better measure of catalytic efficiency.

Q3: What are typical units for K_M?
A: K_M is typically expressed in molarity (M or mol/L).

Q4: Can K_M be determined experimentally?
A: Yes, through methods like Lineweaver-Burk plots or direct measurement of reaction rates at various substrate concentrations.

Q5: What affects the Michaelis Constant?
A: K_M is affected by temperature, pH, enzyme structure, and substrate type.