alostéricos

Alostéricos (singular: alostérico) describes processes and components involved in allosteric regulation, where binding at one site alters activity at another within the same molecule. The term is typically used for proteins such as enzymes and receptors, and for ligands acting at allosteric sites that modulate function.

Allosteric sites are distinct from active sites; ligands binding there are called allosteric effectors. They can be activators or inhibitors. Allosteric regulation can be homotropic (the effector is the substrate) or heterotropic (different molecule).

Two classical models describe cooperativity: Monod-Wyman-Changeux (MWC) and Koshland-Némethy-Filmer (KNF). The MWC model posits a concerted shift between conformations; KNF describes sequential changes upon ligand binding. In many proteins, activity results from ensembles of conformations rather than a simple on/off switch.

Notable examples include hemoglobin, whose oxygen affinity is allosterically regulated; regulatory enzymes such as ATCase and phosphofructokinase; and receptors modulated by allosteric ligands, such as benzodiazepines on GABA-A receptors. In pharmacology, allosteric modulators can offer selectivity and tunable effects, often reducing competitive pressure with endogenous substrates.

Research methods include X-ray crystallography, cryo-electron microscopy, NMR spectroscopy, and fluorescence resonance energy transfer. The term derives from Greek allos 'other' and stereos 'shape', reflecting a change in molecular shape upon ligand binding.