1. What is Catalytic Rate Constant?

Definition: The Catalytic Rate Constant (k_cat) is defined as the rate constant for conversion of the enzyme-substrate complex to enzyme and product.

Purpose: This calculator helps determine the catalytic efficiency of an enzyme based on Michaelis-Menten kinetics parameters.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( k_{cat} \) — Catalytic rate constant (1/s)
• \( K_M \) — Michaelis Constant (mol/m³)
• \( k_f \) — Forward rate constant (1/s)
• \( k_r \) — Reverse rate constant (mol/(m³·s))

Explanation: The formula calculates the catalytic rate constant by accounting for both forward and reverse reaction rates in enzyme kinetics.

3. Importance of Catalytic Rate Constant

Details: k_cat is crucial for understanding enzyme efficiency, determining turnover number, and comparing different enzymes' catalytic power.

4. Using the Calculator

Tips: Enter the Michaelis Constant (K_M), forward rate constant (k_f), and reverse rate constant (k_r). All values must be ≥ 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for k_cat?
A: k_cat values typically range from 1 to 10⁷ s^-1, depending on the enzyme and reaction.

Q2: How does k_cat relate to enzyme efficiency?
A: Higher k_cat values indicate more efficient enzymes that convert substrate to product faster.

Q3: What if my reverse rate constant is zero?
A: If k_r = 0, the calculation simplifies to k_cat = K_M × k_f.

Q4: How do I measure these constants experimentally?
A: K_M and k_cat are typically determined through initial rate measurements at varying substrate concentrations.

Q5: What's the relationship between k_cat and V_max?
A: V_max = k_cat × [E]_total, where [E]_total is the total enzyme concentration.