Enzymhemmstoffen

Enzymhemmstoffe, or enzyme inhibitors, are compounds that decrease or block the activity of enzymes. They can act reversibly or irreversibly and may interact with the active site or with other regions of the enzyme, altering catalysis or substrate binding.

Mechanisms are diverse. Competitive inhibitors resemble the substrate and bind to the enzyme’s active site, so higher substrate concentrations can overcome the inhibition; this increases the apparent Km while leaving Vmax unchanged. Non-competitive, or allosteric, inhibitors bind to a site separate from the active site and reduce Vmax without changing Km. Uncompetitive inhibitors bind only to the enzyme–substrate complex, decreasing both Vmax and Km. Irreversible inhibitors form covalent or very tight bonds with the enzyme, leading to permanent loss of activity.

Types include reversible inhibitors (competitive, non-competitive, and uncompetitive), irreversible inhibitors, substrate analogs, and transition-state inhibitors. Some inhibitors target metalloenzymes by chelating essential metal cofactors, thereby inactivating the enzyme.

Detection and kinetics commonly use parameters such as the inhibition constant (Ki) and the half-maximal inhibitory concentration (IC50) to quantify potency and potency changes under different conditions.

Applications span medicine, agriculture, and research. Many drugs act as enzyme inhibitors to treat disease—for example, statins inhibit HMG-CoA reductase; allopurinol inhibits xanthine oxidase; aspirin inhibits cyclooxygenase; methotrexate inhibits dihydrofolate reductase; HIV protease inhibitors block viral maturation. In agriculture, enzyme inhibitors serve as pesticides or herbicides. In research, inhibitors help delineate metabolic pathways and regulatory mechanisms. Natural inhibitors occur in plants and animals and can influence digestion, metabolism, or defense.