One synthetic complex polypeptide composed of 28 amino acids was successfully sequenced by matrix-assisted laser desorption/ionization-time of flight/time of flight-mass spectrometry (MALDI-TOF/ TOF MS) and electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Depending on the analysis of different sequencing software and the adjustment of the mass spectrometry parameters as well as the laser intensity, the collision induced dissociation (CID) energy and so on, we obtained the perfect tandem mass spectrum which covered all the b- and y-type fragment ions. Results indicated that this method can effectively solve the difficulty occurring in de novo sequencing, such as dead-response of computer. The established method is a good supplement of peptides sequencing for proteomics research.

Key words: tandem mass spectrometry, sequence analysis, polypeptide