Chemistry of Bifunctional Photoprobes: 4. Synthesis of the Chromogenic, Cleavable, Water Soluble, and Heterobifunctional Sulfosuccinimidyl (N-methylamino Perfluoroaryl Azido Benzamido)-ethyl-1,3′-Dithiopropionate: An Efficient Protein Cross-Linking Agent

Synthesis of a new photo cross-linking agent incorporating chromogenicity, cleavability, and water solubility is described. The high efficiency of nitrene insertion observed upon photolysis of perfluoroaryl azides into organic solvents and proteins is extended to the design and synthesis of new multifunctional cross-linking agents useful for protein–protein interactions. The new cross-linker sulfosuccinimidyl (perfluorobenzamido)-ethyl-1,3′-dithiopropionate (SFAD)10was conjugated to IgG and cross-linked to horseradish peroxidase (HRP). The analysis of the cross-linked product using ELISA assays leads to a higher yield of IgG–HRP cross-linked product than that seen with a similar nonfluorinated analog. The efficiency of photo cross-linking by SFAD is also extended to small molecule biotin via CH insertion and checked for the retention of binding affinity of the cross-linked product.