METHODOLOGICAL ASPECTS OF QUANTITATIVE RECEPTOR ASSAYS

Receptor assays occupy a particular position in the methods used in bi oanalysis, as they do not exploit the physico-chemical properties of t he analyte. These assays make use of the property of the analyte to bi nd to the specific binding site (receptor) and to competitively replac e a labelled ligand from the same binding site. The amount of labelled ligand replaced is a measure of the amount as well as the affinity of the analyte. Thus, receptor assays offer additional information about the biological (pharmacological) activity of the analyte by distingui shing the compounds on the basis of their specific binding rather than specific molecular structure (chromatographic and non-chromatographic methods). This paper, starting with the general principles of recepto r-ligand interaction, focuses on the application of ligand-binding tec hniques to the quantitative analysis. The factors which influence the sensitivity and the specificity of quantitative receptor assays, as we ll as the main directions in the improvement of the receptor preparati on by using the solubilized and purified receptor are discussed. In or der to enhance the use of these assays in routine practice, the develo pment of solid-phase receptor assays is considered.