A NEW DIAZIRINE FOR PROTEIN MODIFICATION BY FLASH PHOTOLYSIS: COMPARISON WITH AN AZIDE

Abstract— A new photolabeling agent, N-4–(3-chlorodiazirin-3-yl)benzoyl]glycine (CDBG), a carbene generator, was synthesized. The incorporation of its photolytic products into egg white lysozyme was studied using flash photolysis and compared with incorporation of N-(4-azido-2-nitro-phenyl)-2-amino ethane sulfonate (NAPT) products into lysozyme and bovine pancreatic ribonuclease A. There was considerable additional incorporation of photolysis products into ribonuclease and lysozyme after termination of flash photolysis when NAPT was used but no additional incorporation when CDBG was used. Protein labeled with NAPT retained the label poorly during electrophoresis in sodium dodecyl sulfate. Lysozyme labeled with CDBG lost little label upon electrophoresis. Neither label was well retained during electrophoresis in 8 M urea. Peptic and tryptic peptides from CDBG labeled lysozyme were differentially labeled.