Direct peptide profiling of single neurons by matrix‐assisted laser desorption–ionization mass spectrometry

Peptide profiles of single neurons in Lymnaea stagnalis were directly characterized by matrix‐assisted laser desorption–ionization mass spectrometry. The mass analysis was performed after minor pretreatment and without any separation steps. Good‐quality spectra were obtained of several cell types and also other tissues. The results were compared with the results of conventional peptide chemical methods. In addition to many known peptides, several new peptides were identified. The method provides new opportunities for studying peptide compositions at the single‐cell level, which is shown to have many advantages.