Qualitative and quantitative analysis of wheat gluten proteins by liquid chromatography and electrospray mass spectrometry

Based on analysis by liquid chromatography/electrospray ionisation mass spe ctrometry, we have developed a new method for fast and sensitive fingerprin ting of gliadins and glutenins in wheat flour. Using this procedure the two protein fractions from seven durum wheat varieties have been analysed by h igh resolution high performance liquid chromatographic separation coupled t o accurate determination of molecular mass. In this way, the molecular mass of the single components from both gliadin and glutenin fractions were mea sured and more than forty components were detected for each fraction indica ting a high heterogeneity. Although the chromatographic profiles were simil ar, the molecular masses of protein components with similar retention times among the varieties were often different. The difference ranged from a few mass units corresponding to single amino acid substitution(s) up to thousa nds implying peptide deletion or insertion along the protein chain. Two com ponents representing about a half of the gliadin fraction, e.g, gamma(2)- a nd gamma(3)-gliadin, were identified through the N-terminal sequence and mo lecular mass determination. We suggest the use of the high level and the mo lecular mass of these gliadin components as markers to detect traces of whe at in gluten-free food preparations for celiac patients. Copyright (C) 2000 John Wiley & Sons, Ltd.