Preliminary approaches for the development of a high-performance liquid chromatography/electrospray ionization tandem mass spectrometry method for the detection and label-free semi-quantitation of the main storage proteins of Lupinus albus in foods

Since recent literature has indicated that white lupin (Lupinus albus) may be a useful source of hypocholesterolemic proteins to be used in functional food formulation, our final goal is the development of a fast and automated HPLC /electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) method for the detection and the label-free semi-quantitation of the main lupin globulins in lupin foods and food ingredients. We present here some preliminary results in this direction. As a first step a total protein ext. (TPE-WF) from lupin flakes was pre-fractionated by anion-exchange chromatog. and each fraction was digested with trypsin and analyzed by HPLC/ESI-MS/MS. Subsequently, the tryptic digest of TPE-WF was directly analyzed by HPLC/ESI-MS/MS without any pre-fractionation. Eventually, to test the applicability of the method to real samples, a lupin beverage and 2 lupin protein isolates were analyzed. Both Mascot and Spectrum Mill MS Proteomics Workbench software were used to identify the protein compn. in these samples and Spectrum Mill was used also to test the possibility of developing a label-free semi-quantitation method based on peptide hits. Encouraging results were obtained esp. in the detection of the hypocholesterolemic component b-conglutin. [on SciFinder (R)]