OABK hydrochloride is a small-molecule switch used to control protein activity.

Introducing OABK at position K206 inhibits FLuc enzymatic activity by restricting the access of adenosine triphosphate (ATP) to the active site until the enzyme is deprotected and activated through phosphine treatment. Through the site-specific incorporation of an ortho-azidobenzyloxycarbonyl lysine (OABK)A small-molecule switch for the activation of protein function. Genetically encoded OABK in conjunction with small-molecule activation allows for the conditional regulation of intracellular protein maturation. Deprotection causes the formation of lysine and when OABK is incorporated into a protein, the formation of the active wild-type protein. Incorporation of OABK (0.5 mM) at position K85 of EGFP suppresses fluorophore formation until the native lysine is generated through small-molecule activation (the model is based on Protein Data Bank (PDB). The incorporation of OABK into FLuc blocks the luciferase activity in the absence of small-molecule activation, as determined by a Bright-Glo luciferase assay.