Enzyme Kinetics

Interactive visualization of Michaelis-Menten kinetics, reaction mechanisms, and inhibition patterns

Michaelis-Menten Plot

Velocity vs Substrate Concentration

Normal (No Inhibitor) Competitive Non-competitive Uncompetitive
V_max: 1.00 μM/s
K_m: 1.00 μM
Current Velocity v: 0.00 μM/s
[S]: 0.00 μM

Lineweaver-Burk Plot

Double Reciprocal: 1/v vs 1/[S]

Slope = K_m/V_max: 1.00
Y-Intercept = 1/V_max: 1.00
X-Intercept = -1/K_m: -1.00

Reaction Mechanism: E + S ⇌ ES → E + P

Enzyme
Substrate
ES Complex
Product

Reaction Coordinate Diagram

Activation Energy (E_a): 15.0 kJ/mol
Enzyme Lowers E_a by: 10.0 kJ/mol

Enzyme Kinetics Parameters

Kinetic Parameters

Substrate

Inhibition Type

Inhibitor Concentration

Animation

Michaelis-Menten Equations

Michaelis-Menten: v = V_max·[S]/(K_m + [S])
K_m Definition: K_m = (k₋₁ + k₂)/k₁
V_max Definition: V_max = k₂·[E]_total
Lineweaver-Burk: 1/v = (K_m/V_max)(1/[S]) + 1/V_max

What is Enzyme Kinetics?

Enzyme kinetics is the study of the chemical reactions that are catalyzed by enzymes. In enzyme kinetics, the reaction rate is measured and the effects of varying the conditions of the reaction are investigated. The Michaelis-Menten equation is the most fundamental equation in enzyme kinetics.

Michaelis-Menten Theory

The Michaelis-Menten equation describes the rate of enzymatic reactions by relating reaction rate v to substrate concentration [S]. The equation is derived from the enzyme mechanism: E + S ⇌ ES → E + P, where E is enzyme, S is substrate, ES is enzyme-substrate complex, and P is product. The equation assumes rapid equilibrium or steady-state approximation for the ES complex formation.

Significance of K_m

The Michaelis constant K_m is the substrate concentration at which the reaction rate is half of V_max. It is a measure of the enzyme's affinity for its substrate: a lower K_m indicates higher affinity. K_m is also equal to (k₋₁ + k₂)/k₁, where k₁ is the rate constant for ES formation, k₋₁ is for ES dissociation, and k₂ is for product formation.

Types of Enzyme Inhibition

Competitive Inhibition: Inhibitor binds to the active site, competing with substrate. Increases apparent K_m, V_max unchanged.

Non-competitive Inhibition: Inhibitor binds to allosteric site, affecting enzyme activity. Decreases V_max, K_m unchanged.

Uncompetitive Inhibition: Inhibitor binds only to ES complex. Decreases both V_max and K_m proportionally.

Understanding these inhibition patterns is crucial for drug design and understanding metabolic regulation.

Applications