Affinity label

Affinity labels are molecules similar in structure to a particular substrate for a specific enzyme and are considered to be a class of enzyme inhibitors. These molecules covalently modify active site residues in order to reveal the active site and thus elucidate its structure. The label binds covalently to the enzyme so that the substrate can no longer bind, causing a permanent and irreversible change.

These types of compounds are highly reactive and usually alkylate nucleophilic amino acids present in the enzyme. Their usefulness is limited as they are often indiscriminate in their action, and therefore non-selective and inherently toxic.

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