Radioligandbindingen

Radioligandbindingen is a term used to describe laboratory methods that employ radiolabeled ligands to study interactions with biological targets such as receptors, transporters, or enzymes. The goal is to quantify binding properties, including affinity, density, and kinetics, by measuring how much radioligand associates with the target under defined conditions.

In a typical radioligand binding experiment, a sample containing the target (often membrane preparations or intact cells) is incubated with a radioactively labeled ligand. After incubation, bound ligand is separated from free ligand by filtration, centrifugation, or other separation techniques. The amount of radioactivity in the bound fraction reflects specific binding, which is obtained by subtracting non-specific binding measured in the presence of a large excess of an unlabeled competitor.

Common assay formats include saturation binding, used to determine the dissociation constant (Kd) and receptor density (Bmax); and competition binding, used to estimate the inhibitory constant (Ki) of unlabeled ligands. Kinetic binding experiments can yield association and dissociation rate constants. Data are typically analyzed by nonlinear regression or Scatchard plots, with the basic binding equation B = Bmax × [L] / (Kd + [L]).

Radioligand binding requires radiolabels such as tritium (3H) or iodine-125 (125I), chosen for stability and specific activity. Safety considerations are essential due to radioactivity. Applications span pharmacology and drug discovery, providing insights into receptor pharmacology, ligand selectivity, and functional potential. Limitations include the need for radiolabeled materials and the fact that in vitro binding does not always reflect in vivo behavior.