Identification of a new protein from silkworm pupas by biological mass spectrometry.

To find out the efficient peptide of selenium-rich silkworm pupas in inducing the apoptosis of hepatoma cells, selenium-containing proteins were isolated and characterized. One of the two major proteins in selenium-rich silkworm pupas was identified to be a new protein by peptide mass fingerprinting on matrix assisted laser desorption ionization - time of flight - mass spectrometry. Amino acid sequences of peptides digested by trypsin from the new protein were determined by capillary liquid chromatography - electrospray ionization - quadrupole/time of flight - mass spectrometry and searched with Mascot in NCBI database. Results showed that the six major peptides from the protein were also new peptides that could not be found in the database up to date.