Alloszterikus

Alloszterikus refers to regulation of a protein’s activity through binding at a site separate from the primary active site. The term derives from Greek allos ‘other’ and stereos ‘shape’, indicating a change in conformation induced by effector molecules. Alloszterikus regulation is common in enzymes and receptors and often involves cooperativity among subunits.

Alloszterikus proteins typically have at least two kinds of binding sites: the orthosteric (active) site and an allosteric site. Binding of an effector at the allosteric site can stabilize distinct conformations, promoting (positive allostery) or inhibiting (negative allostery) activity. Classic models describe allostery as either concerted transitions among states (Monod–Wyman–Changeux) or sequential transitions (Koshland–Nemethy–Filmer).

Examples include hemoglobin, where allosteric effectors shift oxygen affinity, and metabolic enzymes such as aspartate transcarbamoylase, regulated by CTP and ATP, or phosphofructokinase, regulated by energy state. In pharmacology, allosteric modulators bind to sites distinct from orthosteric ligands, producing positive allosteric modulators or negative ones, offering therapeutic advantages such as improved specificity and ceiling effects. Allosteric regulation also plays a crucial role in neurotransmitter receptors, including G-protein-coupled receptors and ion channels, where allosteric modulators can fine-tune signaling without directly competing with endogenous ligands.

Understanding alloszterikus is essential for drug design, systems biology, and the study of metabolic regulation, signaling networks, and protein engineering.