Enzyme Kinetics: Michaelis-Menten Simulator

Reaction Conditions

Substrate concentration [S] 40

Enzyme count [E] 6

K_m (affinity, lower = tighter) 30

k_cat (turnover speed) 1.0×

Live Readouts

Reaction rate V

0.0 /s

V / V_max

Product formed

Enzyme sites free

0 / 0

How it works

Each enzyme (green torus) has one active site. A free substrate molecule (blue sphere) that drifts close enough binds the site, briefly forms an enzyme-substrate complex, then is released as product (orange sphere) after a turnover delay set by k_cat. This is the Michaelis-Menten mechanism:

E + S ⇌ ES → E + P
V = Vmax · [S] / (Km + [S])
Vmax = kcat · [E]total

K_m is the substrate concentration at which the rate reaches half of V_max — a smaller K_m means the enzyme binds substrate more tightly and saturates at lower [S]. A competitive inhibitor molecule (red sphere) occupies the active site without reacting, raising the apparent K_m (the enzyme needs more substrate to compete the inhibitor off) while leaving the true V_max unchanged — exactly the kinetic signature used to identify competitive inhibition in a real assay.

[S] slider — number of substrate molecules diffusing in the chamber; more collisions with active sites raise the rate, with diminishing returns near saturation.
[E] slider — number of enzyme molecules (active sites available at once); scales V_max linearly.
K_m slider — controls the binding radius/affinity of each active site.
k_cat slider — how fast a bound complex converts to product and releases the site.
Inhibitor toggle — adds inhibitor molecules that compete for active sites but never turn over.

The small chart in the corner plots reaction rate V against elapsed time, so you can watch the system approach its steady-state rate live.

Enzyme active site Substrate Product Inhibitor

rate V vs time

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