Proteomic analysis of non-toxic Jatropha curcas byproduct cake: Fractionation and identification of the major components

Jatropha curcas non-toxic genotypes have been reported in Mexico and the press-cake, after oil extraction, represents a potential of new source of protein for food and feed uses. However, the characterization of the press-cake proteins is still unknown. The aim of this work was to carry out the molecular characterization of J. curcas seed storage proteins. Proteins in press-cake were pre-fractionated according to the classical Osborne procedure. Main protein fraction in J. curcas cake was represented by glutelins, the electrophoretic analysis showed that glutelins and globulins have the same profile, indicating that oil extraction process could have effect on globulins agglomeration. Protein fractions were analyzed by two-dimensional gel electrophoresis and mass spectrometry, results provide a new dataset of protein species or proteoforms that are accumulated in J. curcas endosperm. The identification of toxic proteins such as curcin in the non-toxic variety could represent that this protein have important roles in seeds. Regulatory proteins such as proteasome subunits and 14-3-3 were identified. A group of different heat shock and stress defense protein species was detected. Proteases related with inhibitory activity against DPPIV were also detected; this could support the potential use of J. curcas cake as nutraceutical food.