Speeding Up Life’s Chemistry

Enzymes are proteins that catalyze (speed up) chemical reactions in cells, making life possible. Their activity can be measured and regulated.

How Enzymes Work

Enzymes lower the activation energy needed for reactions. Substrates bind to the enzyme's active site, forming an enzyme-substrate complex, which then converts to products.

Michaelis-Menten Kinetics

The rate of enzyme activity depends on substrate concentration. The relationship is often described by the Michaelis-Menten equation:

\[ v = \frac{V_{max}[S]}{K_m + [S]} \]

Where:

• \(v\) = reaction rate
• \(V_{max}\) = maximum rate
• \(K_m\) = substrate concentration at half-max rate

Regulation

Enzymes can be regulated by:

• Inhibitors (competitive, noncompetitive)
• Allosteric effectors
• Covalent modification (like phosphorylation)

Why It Matters

Enzyme regulation is crucial for metabolism and disease. Many drugs work by inhibiting enzymes.