Inhibans

Inhibans are substances that reduce or block the activity of a biological target, most often an enzyme or a receptor. They can be small molecules, peptides, proteins, or larger biologicals and may act inside cells or outside cells. Endogenous inhibitors are produced by organisms to regulate metabolism, whereas exogenous inhibitors are introduced as drugs, toxins, or research tools.

Mechanisms of inhibition vary. Competitive inhibitors resemble the natural substrate and vie for the active site, raising the substrate concentration required for a given rate. Noncompetitive inhibitors bind to an allosteric site, altering the enzyme’s conformation and reducing activity regardless of substrate levels. Uncompetitive inhibitors bind only to the enzyme–substrate complex, while mixed inhibitors combine features of these modes. Some inhibitors are irreversible, forming covalent bonds or very tight interactions that permanently inactivate the target. Inhibitors are characterized by kinetic parameters such as Ki (inhibition constant) and IC50 (the concentration giving 50% inhibition); these values depend on assay conditions and target.

Applications span medicine, research, and industry. Therapeutic inhibitors modulate overactive enzymes or receptors to treat disease (for example, protease inhibitors, kinases, and enzyme blockers in cardiovascular or infectious diseases). In the laboratory, inhibitors help define pathways and regulatory checkpoints. In industrial settings, they can regulate catalytic processes or prevent unwanted side reactions.

Physiological and safety considerations include the role of natural inhibition in metabolism, potential off-target effects, and the need for rigorous evaluation of toxicity and pharmacokinetics in drug development.