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 enzyme's affinity for its substrate.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( K_M \) — Michaelis Constant (mol/m³)
• \( k_{cat} \) — Catalytic rate constant (s^-1)
• \( [E_0] \) — Initial enzyme concentration (mol/m³)
• \( S \) — Substrate concentration (mol/m³)
• \( V_0 \) — Initial reaction rate (mol/(m³·s))

Explanation: The formula calculates K_M at low substrate concentrations where the Michaelis-Menten kinetics apply.

3. Importance of Michaelis Constant

Details: K_M is crucial for understanding enzyme efficiency, designing experiments, and predicting enzyme behavior under different conditions.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Ensure values are positive and measured under consistent conditions.

5. Frequently Asked Questions (FAQ)

Q1: What does a low K_M value indicate?
A: A low K_M indicates high enzyme-substrate affinity, meaning the enzyme reaches half its maximum velocity at low substrate concentrations.

Q2: How is k_cat determined experimentally?
A: k_cat is typically determined from the maximum reaction rate (V_max) divided by the total enzyme concentration.

Q3: What are typical units for K_M?
A: K_M is usually expressed in molarity units (mol/m³ or M).

Q4: When is this formula most accurate?
A: This calculation is most accurate under steady-state conditions with excess substrate relative to enzyme.

Q5: How does temperature affect K_M?
A: K_M may change with temperature as it affects enzyme-substrate binding and catalytic efficiency.