Michaelis-Menten Equation Calculator
Calculate enzyme kinetics parameters for single-substrate enzymatic reactions. Find reaction velocity, Vmax, Km, or required substrate concentration.
What is the Michaelis-Menten equation?
The Michaelis-Menten equation describes the rate of enzyme-catalyzed reactions: v = (Vmax × [S]) / (Km + [S]), where v is the reaction velocity, Vmax is maximum velocity, [S] is substrate concentration, and Km is the Michaelis constant (substrate concentration at half Vmax).
What does Km represent?
Km (Michaelis constant) is the substrate concentration at which the reaction velocity is half of Vmax. A low Km indicates high enzyme affinity for the substrate (needs less substrate to achieve half-maximum speed). Km also approximates the dissociation constant when k2 << k1.
How do I determine Vmax and Km experimentally?
Plot the data using a Lineweaver-Burk plot (1/v vs 1/[S]), Eadie-Hofstee plot (v vs v/[S]), or Hanes-Woolf plot ([S]/v vs [S]). The y-intercept gives 1/Vmax and x-intercept gives -1/Km for the Lineweaver-Burk method.
What is the difference between Km and Kcat?
Km is the substrate concentration at half Vmax (affinity measure), while Kcat (turnover number) is the number of substrate molecules converted per enzyme per second at saturation. Kcat/Km is the specificity constant - higher values indicate more efficient enzymes.
Why is the Michaelis-Menten model important?
This model is fundamental to understanding enzyme kinetics, drug metabolism, competitive/non-competitive inhibition, metabolic pathways, and designing enzyme inhibitors for pharmaceuticals. It explains why reaction rates plateau at high substrate concentrations.
What units does Vmax have?
Vmax has units of concentration per time (e.g., M/s, μM/min, mM/s) depending on how velocity is measured. The units depend on the product formation rate or substrate consumption rate in your experiment.