7. Enzyme kinetics. Enzyme units. Factors affecting the enzyme reaction rate: time, temperature, pH, concentration of the enzyme and of the substrate. Michaelis constant. Michaelis – Menten equation and Lineweaver – Burk plot (equation).

Enzyme Kinetics

• Enzyme kinetics is the study of the rates at which enzyme-catalyzed reactions occur and the factors that influence these rates. Understanding enzyme kinetics helps elucidate enzyme mechanisms and predict enzyme behaviour under various conditions.

Definitions:

• Km definition: known as the Michaelis constant; is a key parameter in enzyme kinetics that describes the substrate concentration at which an enzyme achieves half of its maximum reaction velocity (Vmax). In other words, Km is the substrate concentration at which the rate of the enzyme-catalyzed reaction is half of its maximum rate.
• A lower Km value indicates higher substrate affinity, meaning the enzyme can achieve half of its maximum velocity at lower substrate concentrations. Conversely, a higher Km value indicates lower substrate affinity, requiring higher substrate concentrations to reach half-maximal velocity.
• Vmax definition: also known as the maximum reaction velocity, is another key parameter in enzyme kinetics. It represents the maximum rate of an enzyme-catalyzed reaction when the enzyme active sites are fully saturated with substrate.