Enzyme Structure:

• Enzymes are typically globular proteins with a specific three-dimensional shape.

• Their active sites are regions within the enzyme molecule where substrate molecules bind and undergo chemical reactions.

• Enzymes often exhibit a lock-and-key or induced-fit model of substrate binding, where the enzyme’s active site matches the shape and chemical properties of the substrate.

Characteristics of Enzymes:

1. Specificity: Enzymes are highly specific for their substrates, meaning they catalyze particular reactions with particular substrates.

2. Catalytic Activity: Enzymes significantly accelerate the rate of chemical reactions without being consumed in the process.

3. Optimal Conditions: Enzymes function best within specific pH and temperature ranges, known as their optimal conditions.

4. Enzyme-Substrate Complex: During catalysis, enzymes form temporary enzyme-substrate complexes, which lower the activation energy required for the reaction to occur.

5. Regulation: Enzyme activity can be regulated through factors like inhibitors (substances that reduce activity) and activators (substances that increase activity).

Factors Affecting Enzyme Activity:

1. Temperature: Enzymes have an optimal temperature at which they work most efficiently. Above this temperature, they may denature and lose activity.

2. pH: Enzymes have an optimal pH range. Variations in pH can affect the enzyme’s structure and, consequently, its activity.

3. Substrate Concentration: As substrate concentration increases, enzyme activity generally increases until a point of saturation is reached when all enzyme active sites are occupied.

4. Cofactors and Coenzymes: Some enzymes require non-protein molecules called cofactors or coenzymes to function. These can be metal ions or small organic molecules.

5. Inhibitors: Enzyme activity can be inhibited by substances known as inhibitors. Competitive inhibitors compete with the substrate for binding to the enzyme’s active site, while non-competitive inhibitors bind to a different site, altering the enzyme’s shape.

6. Activators: Certain molecules, called activators, can enhance enzyme activity. They may bind to the enzyme and stabilize its active conformation.