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Initial Reaction Rate given Catalytic Rate Constant and Dissociation Rate Constants Calculator

Initial Reaction Rate Formula:

\[ V_0 = \frac{k_{cat} \times [E_0] \times S}{K_D + S} \]

s-1
mol/m3
mol/m3
mol/m3
mol/m3·s

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1. What is Initial Reaction Rate?

Definition: The Initial Reaction Rate (V0) is the speed at which a chemical reaction proceeds at the start of the reaction when substrate concentration is highest.

Purpose: This calculator helps biochemists and enzymologists determine the initial velocity of enzyme-catalyzed reactions using Michaelis-Menten kinetics.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ V_0 = \frac{k_{cat} \times [E_0] \times S}{K_D + S} \]

Where:

Explanation: The formula describes how the reaction rate depends on enzyme and substrate concentrations, and the enzyme's catalytic efficiency and substrate affinity.

3. Importance of Initial Reaction Rate

Details: Measuring initial rates is crucial for understanding enzyme kinetics, determining kinetic parameters, and comparing enzyme efficiency under different conditions.

4. Using the Calculator

Tips: Enter the catalytic rate constant, initial enzyme concentration, substrate concentration, and dissociation constant. All values must be ≥ 0 (except kcat and [E0 which must be > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is kcat?
A: The catalytic rate constant (turnover number) represents the maximum number of substrate molecules converted to product per enzyme molecule per second.

Q2: What does KD represent?
A: The dissociation constant is a measure of enzyme-substrate affinity - lower values indicate tighter binding.

Q3: When is this formula applicable?
A: This applies to simple enzyme kinetics following Michaelis-Menten assumptions (steady-state, single substrate, etc.).

Q4: How do I determine kcat and KD experimentally?
A: These are typically determined by measuring initial rates at varying substrate concentrations and fitting the data.

Q5: What units should I use?
A: Consistent units are required - we use mol/m3 for concentrations (1 mol/m3 = 1 mM).

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