An asymmetrical disulfide-containing photoreactive heterobifunctional reagent designed to introduce radioactive labeling into biological receptors

Abstract

The synthesis of succinimido l-amino-(4-azidosalicyloyl)-3,4-dithio-5-carboxylatea, heterobifunctional photoaffinity labeling reagent, is described. The cross-linker possesses an asymmetrical disulfide bond, and a general method for generating a spacer arm bearing an asymmetrical or symmetrical disulfide bond is detailed. The heterobifunctional reagent has been obtained in a minimum of steps and intermediates have been characterized. It is further shown that the reagent can be trace-labeled with ['25~]-iodinea nd it has been used to modify phytohemagglutinin, a model protein. Upon irradiation, polymeric phytohemagglutinin derivatives are produced, as evidenced by electrophoretic analysis.