Catalytic Rate Constant Formula:
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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.
The calculator uses the formula:
Where:
Explanation: The formula calculates how many reactions each enzyme molecule can catalyze per second when fully saturated with substrate.
Details: kcat is a fundamental parameter in enzyme kinetics that helps compare enzyme efficiencies and understand catalytic mechanisms.
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.
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).