In which type of inhibition does the inhibitor bind only to the enzyme-substrate complex, decreasing both Km and Vmax?

In uncompetitive inhibition, the inhibitor specifically binds only to the enzyme-substrate complex (ES), leading to a reduction in both the Km (Michaelis constant) and Vmax (maximum velocity) of the enzyme-catalyzed reaction. This binding occurs after the substrate has already attached to the enzyme, preventing the conversion of the substrate to product, which decreases the overall rate of reaction.

The decrease in Km in this scenario indicates that the presence of the inhibitor enhances the affinity of the enzyme for the substrate—essentially, the enzyme-substrate complex is favored and more stable. As a result, a lower concentration of substrate is needed to reach half of the maximum velocity, which is reflected in the lower Km value. Simultaneously, because the inhibitor hinders the formation of product, the Vmax is reduced because even at saturating substrate concentrations, the maximum rate of the reaction falls due to the presence of the inhibitor.

Uncompetitive inhibition is distinct from other forms of inhibition like competitive or noncompetitive inhibition. Competitive inhibitors bind to the free enzyme and increase the Km without affecting Vmax, while noncompetitive inhibitors can bind to both free enzymes and the enzyme-substrate complex, affecting the Vmax but not the Km. Allosteric inhibition involves