The lyophilized conjugate vaccine Bm86-Ac-Cys 1 pP0 was dissolved in 1% (w/v), pH=8.3 ammonium bicarbonate solution and was heated at 37 o C during 12 hours to transform the thiosuccinimide linker in the hydrolyzed form . The resultant conjugate was reduced and S-alkylated by using a standard protocol and later digested in tandem with Lysyl-endopeptidase (LEP, Wako, Japan) overnight and trypsin for additional six hours at the same temperature. The mixture of proteolytic peptides was acidified with 2 % of formic acid, desalted by using C18-Ziptip from Millipore following manufacturer instructions. The peptides eluted in an 60 % acetonitrile/1 % of formic acid solution were freeze and lyophilized, and kept at -20 o C until LC-MS/MS analysis.