Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids.

Synonyms: Affinity Labeling Reagents, Affinity Labels, 0, Reagents, Affinity Labeling, Labels, Affinity, Labeling Reagents, Affinity