1. What is Enzyme Inhibitor Dissociation Constant?

Definition: The Enzyme Inhibitor Dissociation Constant (K_i) measures the affinity between an enzyme and its inhibitor.

Purpose: It helps biochemists understand enzyme inhibition mechanisms and design effective inhibitors for therapeutic or research purposes.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( K_i \) — Enzyme inhibitor dissociation constant (mol/m³)
• \( I \) — Inhibitor concentration (mol/m³)
• \( [E_0] \) — Initial enzyme concentration (mol/m³)
• \( E_{0app} \) — Apparent initial enzyme concentration (mol/m³)

Explanation: The formula calculates the dissociation constant by comparing the apparent enzyme concentration in the presence of inhibitor with the actual enzyme concentration.

3. Importance of Dissociation Constant

Details: A lower K_i value indicates stronger inhibitor binding. This is crucial for drug development and understanding metabolic pathways.

4. Using the Calculator

Tips: Enter the inhibitor concentration, initial enzyme concentration, and apparent initial enzyme concentration. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What does a high K_i value indicate?
A: A high K_i indicates weak binding between the enzyme and inhibitor.

Q2: How is apparent enzyme concentration different from actual concentration?
A: Apparent concentration is measured in the presence of inhibitor and reflects reduced enzyme activity.

Q3: What units should I use for concentrations?
A: The calculator uses mol/m³, but you can convert from molarity (M) by multiplying by 1000 (1 M = 1000 mol/m³).

Q4: Can this calculator be used for competitive inhibitors?
A: This specific formula is for non-competitive inhibitors. Competitive inhibitors require a different calculation.

Q5: What's a typical range for K_i values?
A: K_i values typically range from 10^-12 to 10^-3 mol/m³, depending on the enzyme-inhibitor pair.