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Catalytic Rate Constant if Substrate Concentration is higher than Michaelis Constant Calculator

Catalytic Rate Constant Formula:

\[ k_{cat} = \frac{V_{max}}{[E_0]} \]

mol/m³·s
mol/m³

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1. What is Catalytic Rate Constant?

Definition: The catalytic rate constant (kcat) represents the number of substrate molecules converted to product per enzyme molecule per second when the enzyme is saturated with substrate.

Purpose: It measures the enzyme's maximum catalytic efficiency under saturating substrate conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ k_{cat} = \frac{V_{max}}{[E_0]} \]

Where:

Explanation: The formula calculates how many reactions each enzyme molecule can catalyze per second when fully saturated with substrate.

3. Importance of Catalytic Rate Constant

Details: kcat is a fundamental parameter in enzyme kinetics that helps compare enzyme efficiencies and understand catalytic mechanisms.

4. Using the Calculator

Tips: Enter Vmax in mol/m³·s and [E0] in mol/m³. Both values must be > 0. The calculator assumes substrate concentration is much higher than KM.

5. Frequently Asked Questions (FAQ)

Q1: What does a higher kcat value mean?
A: A higher kcat indicates a more efficient enzyme that can process more substrate molecules per second.

Q2: How is kcat different from KM?
A: While kcat measures catalytic efficiency at saturation, KM reflects the substrate concentration needed for half-maximal velocity.

Q3: What are typical kcat values?
A: kcat values range from <1 s⁻¹ for slow enzymes to >10⁶ s⁻¹ for very efficient enzymes.

Q4: How does temperature affect kcat?
A: kcat generally increases with temperature until the enzyme denatures.

Q5: Can kcat be greater than diffusion limits?
A: No, kcat cannot exceed the rate at which substrate can diffuse to the enzyme's active site (~10⁸-10⁹ M⁻¹s⁻¹).

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