Biological Chemistry - Factors Affecting Enzyme Activity

Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy ($E_a$) required for the reaction to occur.

Temperature: As temperature increases, the kinetic energy of molecules increases, leading to more frequent collisions between the enzyme and substrate. However, beyond the optimum temperature ($T_{optimum}$), the enzyme's tertiary structure breaks down (denaturation), and the active site loses its shape.

pH Level: Most enzymes have an optimum pH where they function most efficiently. Extreme acidic or alkaline conditions can disrupt the ionic and hydrogen bonds in the enzyme, leading to denaturation.

Substrate Concentration: Increasing the concentration of substrate increases the rate of reaction up to a point. Once all active sites are occupied (saturation), the reaction reaches its maximum velocity ($V_{max}$), and further increases in substrate concentration will not affect the rate.

Enzyme Concentration: If substrate is in excess, increasing the enzyme concentration linearly increases the rate of reaction because more active sites are available for catalysis.