Substrate Concentration Formula:
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Definition: This calculator determines the substrate concentration when the Michaelis constant is much larger than the substrate concentration, using enzyme kinetics parameters.
Purpose: It helps biochemists and enzymologists understand reaction dynamics when substrate concentration is significantly lower than KM.
The calculator uses the formula:
Where:
Explanation: When KM ≫ S, the reaction follows first-order kinetics with respect to substrate.
Details: Understanding substrate concentration under these conditions is crucial for enzyme characterization, drug development, and metabolic pathway analysis.
Tips: Enter all positive values for initial reaction rate, Michaelis constant, catalytic rate constant, and initial enzyme concentration.
Q1: When is KM ≫ S a valid assumption?
A: This applies when substrate concentration is less than 10% of KM, common in early reaction stages or dilute conditions.
Q2: How do I measure V₀ experimentally?
A: Measure product formation or substrate disappearance in the first 5-10% of reaction progress.
Q3: What's a typical kcat value?
A: kcat ranges from 0.1 to 10⁶ s⁻¹ depending on the enzyme and reaction.
Q4: Why is enzyme concentration important?
A: [E₀] affects the maximum reaction rate (Vmax = kcat[E₀]).
Q5: Can I use different concentration units?
A: Yes, but all concentrations must use consistent units (e.g., all in mol/m³ or all in mM).