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Michaelis-Menten Calculator

Enzyme reaction kinetics.

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Velocity

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Overview

The Michaelis-Menten equation models the rate of enzymatic reactions by relating the reaction velocity to the concentration of a substrate. It describes a system where an enzyme binds a substrate to form a complex, which then converts into a product and releases the enzyme, assuming the system is in a steady state.

Symbols

Variables

v = Velocity, = Max Velocity, [S] = Substrate Conc, = Michaelis Const

Velocity
mM/s
Max Velocity
mM/s
[S]
Substrate Conc
mM
Michaelis Const
mM

Apply it well

When To Use

When to use: Apply this equation to determine the kinetic parameters of simple non-allosteric enzymes where the reaction rate eventually levels off at high substrate concentrations. It assumes that the concentration of the enzyme-substrate complex remains constant and that the reverse reaction of product to substrate is negligible.

Why it matters: This model is foundational for understanding enzyme efficiency and substrate affinity, which are critical for pharmacology and drug development. It allows researchers to calculate Km, which represents the substrate concentration required to reach half the maximum velocity, providing a standardized measure of how tightly an enzyme binds its substrate.

Avoid these traps

Common Mistakes

  • Using S in the wrong units.
  • Forgetting Km is added in the denominator.

One free problem

Practice Problem

A specific enzyme-catalyzed reaction has a maximum velocity (Vmax) of 100 µmol/min and a Michaelis constant (Km) of 5 mM. Calculate the reaction velocity (v) when the substrate concentration (S) is 5 mM.

Max Velocity100 mM/s
Michaelis Const5 mM
Substrate Conc5 mM

Solve for:

Hint: Recall that when the substrate concentration equals the Michaelis constant, the velocity is half of Vmax.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Lehninger Principles of Biochemistry
  2. Voet & Voet Biochemistry
  3. Wikipedia: Michaelis–Menten kinetics
  4. IUPAC Gold Book: Michaelis constant
  5. IUPAC Gold Book: Michaelis-Menten kinetics
  6. Lehninger Principles of Biochemistry, 8th Edition (Nelson, D.L., Cox, M.M.)
  7. Nelson, D. L., Cox, M. M. (2017). Lehninger Principles of Biochemistry (7th ed.). W. H. Freeman.
  8. Voet, D., Voet, J. G., Pratt, C. W. (2016). Fundamentals of Biochemistry: Life at the Molecular Level (5th ed.). Wiley.