Topic 3) Enzymes (AS)

Enzyme-Substrate Specificity

Enzymes are highly specific to their substrates due to the unique shape and chemical properties of their active sites.

Lock and Key Model

The substrate fits precisely into the enzyme's active site, forming an enzyme-substrate complex.

Induced Fit Model

The enzyme's active site undergoes a change upon substrate binding, enhancing the fit between enzyme and substrate.

Lowering Activation Energy

Enzymes lower the activation energy required for a reaction, increasing the rate of reaction.

Enzyme-Substrate Complex

Formed when the enzyme binds to the substrate, undergoing a reaction to produce final products.

Effects of Temperature on Enzymes

Increasing temperature generally increases reaction rates, while extreme temperatures can cause denaturation.

Optimum Temperature for Human Enzymes

Most human enzymes have an optimum temperature around 37–40°C.

Optimum pH for Enzymes

Each enzyme operates best at a specific pH, with deviations potentially causing decreased activity.

Substrate Concentration Effect

Increasing substrate concentration raises reaction rates until all active sites are occupied.

Competitive Inhibitors

Compete with the substrate for the active site, decreasing the rate of reaction.

Non-Competitive Inhibitors

Bind to an allosteric site, altering the enzyme's shape and reducing activity.

Coenzymes and Cofactors

Coenzymes are organic molecules that assist enzymes, while cofactors are inorganic ions essential for enzyme activity.