Synthesis and biological characterization of sqbazide, a novel biotinylated photoaffinity probe for the study of the human platelet thromboxane A2 receptor.

SQBAzide, a biotinylated, azido derivative of the TXA2 receptor antagonist, SQ31,491, was synthesized and characterized. The compound specifically inhibited human platelet aggregation mediated by TXA2 receptor activation and irreversibly labeled platelet TXA2 receptors upon exposure to ultraviolet light. This probe should prove to be of significant value for the study of the receptor-ligand binding domain.