Study of exceed micro-endopeptidease and enzymolysis produces of acidic peptide from the Aplysia cerebral ganglion by mass spectrometry

Acidic peptide (AP) consisting of 27 residues of amino acids was synthesized by the peptide synthetic instrument, and its primary structure was further analyzed with electrospray ionization-Q-time of flight (ESI-Q-TOF) mass spectrometer. The composition and distribution of the peptides and proteome in Aplysia cerebral ganglion were separated and identified by a combined off- line technology of reversed phase-high performance liquid chromatography (RP-HPLC ) and matrix-assisted laser desorption ionization (MALDI)-TOF mass spectrometry, respectively. A lot of enzymolysis produces of AP in cerebral ganglion(CG) were found, which showed a dipolymer molecular structure. It was noticed that the primary structure of these peptides were found to share a similar dipolymer structures with 2(NKDEEQRELLKAISNLL) ,2 (NKDEEQRELLKAISNL)., 2(SGVSLLTSNKDEEQREL), and 2(LTSNKDEEQRELL) and to have same L-R(amino acids) residues of bound split. Using a combined method of AP as an probe and MALDI-TOF mass spectrometry as a analytical technology, it was found that there was the exceed micro-endopeptidease for enzymolysis L-R bound of AP in CG, indicating that its molecular weight was 78218. 25 Da. In addition, the analytical method described here is also fit for finding composition and distribution of the exceed micro-peptide and endo-peptidease in various organisms.