Investigation of beta-amyloid peptide by on-line high-performance liquid chromatography coupled to electrospray ionization mass spectrometry.

beta(1-39) amyloid peptide is one of the components of the cerebral amyloid deposits that are characteristic of Alzheimer's disease. Solid-phase synthesis of this peptide resulted in a fairly complex crude product containing both the target peptide and a number of side products. High-performance liquid chromatography coupled to electrospray ionization mass spectrometry allowed rapid and reliable identification of both the desired peptide and most of the side products which were found to have relative molecular masses above and below that of the target peptide.