Comparison of the Reactivity of Carbohydrate Photoaffinity Probes with Different Photoreactive Groups

Abstract A judicious choice of photoreactive group is critical in successful photoaffinity labeling studies of small molecule–protein interactions. A set of carbohydrate‐based photoaffinity probes was prepared to compare the effects of three major photoreactive groups on the efficiency and selectivity of crosslinking a binding protein with low affinity. We showed that, despite the low crosslinking yield, the diazirine probe displayed the high ligand‐dependent reactivity consistent with the ideal mechanism of photoaffinity labeling. Moreover, we demonstrated that, among the three photoreactive groups, only the diazirine probe achieved highly selective crosslinking of a low‐affinity binding protein in cell lysate.