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)
• \( S \) — Substrate Concentration (mol/m³)
• \( k_{cat} \) — Catalytic Rate Constant (s⁻¹)
• \( [E_0] \) — Initial Enzyme Concentration (mol/m³)
• \( V_0 \) — Initial Reaction Rate (mol/m³·s)

Explanation: The formula calculates K_M based on the relationship between substrate concentration, enzyme concentration, catalytic rate, and initial reaction rate.

3. Importance of Michaelis Constant

Details: K_M is crucial for understanding enzyme kinetics, determining enzyme efficiency, and comparing different enzymes or substrates.

4. Using the Calculator

Tips: Enter all required values in appropriate units. All values must be positive numbers. Typical ranges:

• Substrate Concentration: 0.001-1000 mol/m³
• Catalytic Rate Constant: 0.1-10⁶ s⁻¹
• Enzyme Concentration: 10⁻⁹-10⁻³ mol/m³
• Initial Reaction Rate: 10⁻⁹-10⁻³ mol/m³·s

5. Frequently Asked Questions (FAQ)

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

Q2: How is K_M related to V_max?
A: K_M is the substrate concentration at which reaction rate is half of V_max.

Q3: What factors affect K_M?
A: Temperature, pH, enzyme and substrate types, and presence of inhibitors or activators.

Q4: Can K_M be negative?
A: No, K_M is always positive as it represents a concentration.

Q5: How is K_M determined experimentally?
A: Typically through Lineweaver-Burk plots or other kinetic studies measuring reaction rates at various substrate concentrations.