Abstract
We performed proteome analyses on the pod husk of cacao (Theobroma cacao), a tropical tree which is cultivated primarily for its beans for making chocolate. Protein identification was done by de novo sequence similarity data searching approach due to incomplete genome database. Easy and yet unambiguous interpretation of MALDI-TOF PSD spectra was achieved with the aid of N-terminal sulfonation of tryptic peptides using 4-sulfophenyl isothiocyanate. Currently, we have identified 51 proteins from 89 major proteins analyzed. We also performed differential proteome analyses between two cacao clones, LAFI7 and ICS39. LAFI7 is a resistant clone against Conopomorpha cramerella, the most destructive insect pest of cacao in South-East Asian countries, while ICS39 is the most susceptible clone. Several spots in 2-DE have been found to be differentially expressed, specifically, L212 (24.7 kDa/6.3) in LAFI7 and i212 (21.4 kDa/6.4) in ICS39. We successfully de novo sequenced four tryptic peptides that are shared by both proteins. Database searches show that L212 and i212 have strong similarity to ASR proteins.
