Enzyme kinetics and inhibition

In this talk, we turn our attention to enzyme kinetics and inhibition, framing our discussion around enzyme–substrate interactions, reaction rates, and how enzymes influence biochemical pathways without altering equilibrium or thermodynamics. To understand enzyme function, we measure how initial reaction velocity changes with substrate concentration. The Michaelis-Menten equation describes this, yielding two key parameters: Vmax, the maximal rate when the enzyme is fully saturated, and Km, the substrate concentration at half-maximal velocity. A low Km means high substrate affinity, while a high Km indicates low affinity. The resulting hyperbolic curve typifies Michaelis-Menten kinetics. This approach allows for effective comparison of enzymes and assessment of the impact of mutations or regulators on activity. Enzymes lower the activation energy barrier by stabilizing the transition state, which is key to their catalytic efficiency. Several external factors influence enzyme activity: Temperature increases reaction speed until the enzyme denatures; pH alters the ionization states of amino acids in the active site, with each enzyme having an optimal pH range. Other influences include ionic strength, cofactors or metal ions, and substrate concentration. Enzymes are highly precise but sensitive to their environment. Enzyme inhibition is central