Structural elucidation of a peptide from a single neuron by matrix-assisted laser desorption/ionization employing a tandem double focusing magnetic-orthogonal acceleration time-of-flight mass spectrometer

An AutoSpec-Tof mass spectrometer, in the configuration of a matrix-assisted laser desorption/ionization source, a trisector mass spectrometer, a high-energy collision chamber, and a time-of-flight mass spectrometer, was used for direct structural characterization of a tetrapeptide from a single identifiable neuron. Peptides from the freshly dissected snail neuron were desorbed and ionized by the matrix-assisted laser desorption/ionization source. A molecular species with a protonated mass of 429 Da was selected as the parent ion and fragmented in the high-energy collision chamber with xenon gas at 800 eV, producing daughter ions that were detected with a time-of-flight detector, The various ion series were recorded and, together, show that the parent ion has the primary structure of AGPWamide.