MATRIX-ASSISTED LASER DESORPTION IONIZATION MASS-SPECTROMETRIC PEPTIDE-MAPPING OF THE NEURAL CELL-ADHESION PROTEIN NEUROLIN PURIFIED BY SODIUM DODECYL-SULFATE POLYACRYLAMIDE-GEL ELECTROPHORESIS OR ACIDIC PRECIPITATION/

Neurolin is a cell surface protein involved in the neural regeneration and neogenesis of the central nervous system of goldfish, Its theoret ical molecular mass, based on the amino acid sequence translated from the cDNA, is 58 kDa, but in SDS-PAGE it shows an apparent MW of 86 kDa . Neurolin is stated to be a glycoprotein and it contains five potenti al N- and 96 potential O-glycosylation sites. The complete characteriz ation of the primary structure and initial investigations on the postu lated glycosylation of neurolin, immunopurified from goldfish brains, are described. The protein was either digested in situ in the sodium d odecyl sulfate polyacrylamide gel matrix or digested after trichloroac etic acid precipitation. Trypsin and endoprotease Glu-C were used as p roteases and matrix-assisted laser desorption/ionization mass spectrom etry was applied for direct peptide mapping analysis of the proteolyti c mixtures. Various sample preparation techniques were performed and t he mass spectra were recorded in both positive- and negative-ion modes . (C) 1997 by John Wiley & Sons, Ltd.