Enzyme Kinetics Simulator | mysimulator.uk

Substrate & Inhibitor

Substrate [S] 10.0 mM

Inhibitor [I] 5.0 mM

Live measurement

Rate v

–

v / Vmax

–

Km (apparent)

–

Vmax (true)

–

Kinetic data

Fitted Km

–

Fitted Vmax

–

Record at least 2 points (or run auto-sweep) to fit the Lineweaver-Burk line.

How it works

The reaction obeys the Michaelis-Menten equation: the rate v rises with substrate concentration [S] but saturates as every enzyme molecule becomes occupied. A competitive inhibitor competes with the substrate for the same active site, so it raises the apparent Km without changing the true Vmax — enough substrate always out-competes it eventually.

v = Vmax·[S] / (Km,app + [S])
Km,app = Km·(1 + [I]/Ki)   (competitive)

1/v = (Km,app/Vmax)·(1/[S]) + 1/Vmax   (Lineweaver-Burk)

[S] — substrate concentration fed to the enzyme population; drives the reaction chamber's binding activity directly.
Competitive inhibitor — when on, inhibitor molecules occupy the same active site as substrate. It shifts the Michaelis-Menten curve rightward (higher apparent Km) but the curve still reaches the same Vmax at high [S].
Record point / Auto-sweep — measures v at the current (or a swept range of) [S] with realistic experimental noise and plots it on both graphs, exactly like a real kinetics assay.
Lineweaver-Burk plot — plotting 1/v against 1/[S] turns the hyperbola into a straight line: its slope is Km,app/Vmax, its y-intercept is 1/Vmax, and its x-intercept is −1/Km,app. The fitted panel reads Km and Vmax straight off those intercepts from your own simulated data.

Real-world relevance: this is exactly how biochemists first characterize a new enzyme or screen a drug candidate as a competitive inhibitor — by fitting initial-rate measurements across a range of substrate concentrations and linearizing the result.

Free enzyme Enzyme–substrate (ES) Enzyme–inhibitor (EI)