Michaelis-Menten Equation Calculator

Your details

Pick the parameter you want to calculate. The other three become your inputs.
Unit used for [S], Km, and the concentration part of velocity.
Time unit used for Vmax and v.
Concentration of the substrate in the reaction mixture. Leave this blank when solving for [S].
uM
The maximum reaction velocity reached when the enzyme is fully saturated with substrate. Leave blank when solving for Vmax.
uM/s
The substrate concentration at which the reaction rate is half of Vmax. A low Km means the enzyme reaches half-Vmax at a low substrate concentration (high affinity).
uM
Result
v = 71.43 uM/s

The calculated Michaelis-Menten parameter

Reaction velocity (v)71.43 uM/s
Maximum velocity (Vmax)100 uM/s
Michaelis constant (Km)20 uM
Substrate concentration [S]50 uM
Saturation fraction (v/Vmax)71.4%
Half-saturation condition[S] (50 uM) is above Km - enzyme is above half-saturation
71.4% v/Vmax
Linear region<10%Below half-Vmax10%-50%Transition region50%-90%Near saturation90%+

Enzyme is at 71.4% saturation

  • The enzyme is operating at 71.4% of its maximum velocity (approaching saturation).
  • Km represents the substrate concentration that gives exactly half-Vmax. A low Km means the enzyme binds substrate tightly; a high Km means more substrate is needed to half-saturate the enzyme.
  • The system is in the hyperbolic transition region of the curve. Increasing [S] still raises velocity measurably, but the rate of gain is declining.
  • The Michaelis-Menten model assumes single-substrate kinetics, a steady-state intermediate (ES complex), and no product inhibition. Real assay conditions may deviate from these assumptions.

Next stepTo measure Km and Vmax experimentally, vary [S] across a range spanning roughly 0.1 Km to 10 Km, plot the resulting velocities (uM/s), and fit the hyperbolic curve or use a Lineweaver-Burk double-reciprocal plot.

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