Nonkompetitif

Nonkompetitif, or noncompetitive inhibition, is a form of enzyme inhibition in biochemistry. In this mode, an inhibitor binds to the enzyme at a site distinct from the active site, and the binding can occur whether or not the substrate is bound. This interaction reduces the catalytic efficiency of the enzyme without necessarily preventing substrate binding.

In pure noncompetitive inhibition, the inhibitor has the same affinity for the free enzyme (E) and for the enzyme–substrate complex (ES). As a result, the maximum reaction rate (Vmax) decreases, while the Michaelis constant (Km) remains unchanged. In mixed noncompetitive inhibition, the inhibitor binds with different affinities to E and ES, leading to a decrease in Vmax and a change in Km (either increase or decrease depending on relative affinities).

Kinetic patterns: On a Lineweaver-Burk plot, pure noncompetitive inhibition yields lines that intersect at the x-axis (same Km, different 1/Vmax). Mixed inhibition yields lines that intersect left of the y-axis (Km changed).

Applications and context: Noncompetitive inhibition is a mechanism of metabolic regulation and is an important consideration in drug design, where allosteric inhibitors modulate enzyme activity without competing with substrate binding. The term is used in pharmacology and biochemistry in several languages, including Indonesian, where nonkompetitif is the equivalent of noncompetitive.