Prediction of the amino acid composition of small peptides contained in a plant protein hydrolysate by LC-MS and CE-MS

An original procedure is described to propose the amino acid composition of small peptides (molar mass < 1000 g/mol) contained in a complex vegetable protein hydrolysate. This method is based on two predictive models: the first is related to the peptide hydrophobic character using reversed-phase liquid chromatography-mass spectrometry analysis; the second to the peptide charge-to-mass ratio using capillary electrophoresis-mass spectrometry analysis. A software has been developed to determine the possible amino acid combinations as a function of the mass determination and of the data provided by both models. This computer-aided method has been applied to a rapeseed protein hydrolysate. In the hydrolysate, the amino acid sequence of some unknown vegetable peptides has been determined, using the sequences of native proteins.