1. What is Catalytic Rate Constant?

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

Purpose: It measures the turnover number of an enzyme, indicating how many substrate molecules one enzyme molecule can convert to product per second.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( k_{cat} \) — Catalytic rate constant (1/s)
• \( k_f \) — Forward rate constant (1/s)
• \( E \) — Catalyst concentration (mol/m³)
• \( S \) — Substrate concentration (mol/m³)
• \( ES \) — Enzyme-substrate complex concentration (mol/m³)
• \( k_r \) — Reverse rate constant (mol/(m³·s))

Explanation: The formula calculates the net catalytic rate by considering both forward and reverse reaction rates.

3. Importance of Catalytic Rate Constant

Details: k_cat is crucial for understanding enzyme efficiency, designing enzymatic reactions, and comparing different catalysts.

4. Using the Calculator

Tips: Enter all required values in appropriate units. Forward rate constant and concentrations must be positive values.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for k_cat?
A: k_cat values vary widely but typically range from 1 to 10⁶ s^-1 for different enzymes.

Q2: How does k_cat relate to enzyme efficiency?
A: Higher k_cat values indicate more efficient enzymes that process more substrate molecules per second.

Q3: What if my reverse rate constant is zero?
A: If the reaction is essentially irreversible (k_r ≈ 0), you can enter zero for k_r.

Q4: How do I measure enzyme-substrate complex concentration?
A: ES can be measured using spectroscopic methods or determined from kinetic experiments.

Q5: What's the difference between k_cat and K_m?
A: k_cat measures catalytic efficiency, while K_m reflects substrate binding affinity.