N-bromoacetyl-p-azido-L-phenylalanine methyl ester: a bifunctional chemically and photo-activated cross-linking reagent

A cross-linking reagent with individually controllable functional groups, N-bromoacetyl-p-azido-l-phenylalanine methyl ester, has been developed. When reacted with endoplasmic reticulum membranes stripped of their ribosomes, the bromoacetyl group is most active at basic pH, reacts only with protein, and has biphasic reaction kinetics. Although the azido function also has biphasic reaction kinetics, the extent of the irradiated reaction is different from that of the dark reaction. In addition, the azido function reacts both with protein and with RNA. In a cross-linking experiment, no cross-linking occurred until the reagent-membrane complex was irradiated, even though the complex underwent limited exposure to light. Upon irradiation, extensive cross-linking occurred.