PHOTOLABELING OF HUMAN SERUM-ALBUMIN BY 4-AZIDO-2-([C-14]-METHYLAMINO) TRIFLUOROBENZONITRILE - A HIGH-EFFICIENCY, LONG-WAVELENGTH PHOTOLABEL

N-alkyl derivatives of perfluoroarylazides are excellent candidates fo r photolabeling of proteins since they have absorption spectra in the 340-350 nm range permitting photolabel absorption without direct prote in photolysis. The [C-14]-N-methylamino derivative of 4-azido-tetraflu orobenzonitrile has been used to demonstrate that 80% of the photo-ind uced nitrene transient becomes covalently attached to HSA during photo lysis. Multiwavelength detection of the photoprobe-protein separation by size exclusion chromatography is shown to be an effective tool for assessing the conjugation of the photoprobe to the protein.