CAPILLARY ZONE ELECTROPHORESIS IONSPRAY MASS-SPECTROMETRY OF A SYNTHETIC DRUG PROTEIN CONJUGATE MIXTURE

Low-molecular-mass proteins, such as lysozyme, may be suitable carrier s to target drugs to the kidney. Naproxen, an anti-inflammatory drug, has been conjugated with lysozyme via a covalent amide bond formed bet ween the carboxylic acid function of naproxen and the amino group of o ne of the lysines in lysozyme. The reaction products were analysed by capillary electrophoresis-ionspray mass spectrometry. Native lysozyme and its conjugates with one, two and three naproxen molecules were sep arated and their identities were confirmed by mass spectrometry. The i on current profiles of the individual conjugates showed pH-dependent t ailing and adsorption-desorption phenomena in the capillary electropho resis column not observed in the total ion current profiles and not ob servable by UV detection.