Enzyme Kinetics (Michaelis-Menten) Calculator Formula

Understand the math behind the enzyme kinetics (michaelis-menten) calculator. Each variable explained with a worked example.

Formulas Used

Reaction Velocity (v)

velocity = vmax * substrate / (km + substrate)

v / Vmax

v_over_vmax = substrate / (km + substrate)

Variables

VariableDescriptionDefault
vmaxMaximum Velocity (Vmax)(umol/min)100
kmMichaelis Constant (Km)(uM)50
substrateSubstrate Concentration [S](uM)25

How It Works

Michaelis-Menten Enzyme Kinetics

The Michaelis-Menten equation describes the rate of enzyme-catalyzed reactions as a function of substrate concentration.

Formula

v = Vmax × [S] / (Km + [S])

where Vmax is the maximum velocity, Km is the substrate concentration at half-Vmax, and [S] is the substrate concentration. When [S] = Km, v = Vmax/2. When [S] >> Km, v approaches Vmax.

Worked Example

An enzyme with Vmax = 100 umol/min and Km = 50 uM at [S] = 25 uM.

vmax = 100km = 50substrate = 25
  1. 01v = 100 × 25 / (50 + 25)
  2. 02v = 2500 / 75 = 33.33 umol/min
  3. 03v/Vmax = 25/75 = 0.333 (33.3% of Vmax)