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Enzyme Substrate Complex Concentration given Forward, Reverse, and Catalytic Rate Constant Calculator

Enzyme Substrate Complex Concentration Formula:

\[ ES = \frac{k_f \times E \times S}{k_r + k_{cat}} \]

s-1
mol/m3
mol/m3
mol/m3·s
s-1

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1. What is Enzyme Substrate Complex Concentration?

Definition: The Enzyme Substrate Complex Concentration (ES) is the concentration of the intermediate formed when an enzyme binds to its substrate during a biochemical reaction.

Purpose: This calculation is essential for understanding enzyme kinetics and determining reaction rates in biochemical systems.

2. How Does the Calculator Work?

The calculator uses the Michaelis-Menten derived formula:

\[ ES = \frac{k_f \times E \times S}{k_r + k_{cat}} \]

Where:

Explanation: The formula calculates the steady-state concentration of the enzyme-substrate complex based on the reaction rates and concentrations.

3. Importance of ES Calculation

Details: Understanding ES concentration helps in determining reaction mechanisms, enzyme efficiency, and designing enzyme inhibitors for medical applications.

4. Using the Calculator

Tips: Enter all rate constants and concentrations. Values must be positive numbers. Typical units are shown for each parameter.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for kf?
A: Forward rate constants typically range from 10⁴ to 10⁸ M⁻¹s⁻¹ for enzyme-substrate binding.

Q2: How does kcat affect ES concentration?
A: Higher kcat values generally lead to lower ES concentrations as the complex is converted to product more quickly.

Q3: What if kr is zero?
A: If the reverse reaction is negligible (kr ≈ 0), the formula simplifies to ES = (kf × E × S)/kcat.

Q4: How is this related to Michaelis-Menten kinetics?
A: This is part of the derivation of the Michaelis-Menten equation, where ES is the central intermediate.

Q5: What units should I use?
A: Consistent units are required - mol/m³ for concentrations, s⁻¹ for rate constants, and mol/m³·s for kr.

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