Glycoproteins and Protein Glycations Identified in Barley Grain and Malt by 2D-HPLC and MS/MS

J. Žídková¹, I. Petry-Podgórska², M. Laštovičková¹, J. Bobáĺová¹

¹Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Veveří 97, 60200 Brno, Czech Republic

²Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Vídeňská 1083, 14660 Prague 4, Czech Republic

zidkova@iach.cz

Carbohydrate moieties represent typical post-translational modifications of barley proteins. Binding of mono- and oligosaccharides to polypeptide chain can be either a physiological reaction, glycosylation, or an artificial process occurring during industrial processing, glycation. Both types of modification have important consequences for consumers of barley products. Glycation changes physical and chemical properties of malt and other products, and several glycoproteins were described as important allergens. Two-dimensional liquid chromatography (ion-exchange and reversed-phase) with off-line mass-spectrometric detection (MALDI-TOF-MS/MS) has been used to analyze glycoproteins and glycated proteins in barley grain and malt. Seven glycoproteins were identified by partial sequencing based on fragmentation MS/MS spectra. Glycations were observed for five out of 16 unambiguously assigned proteins in malt extract, while no glycation was detected in barley grains. The results document that the proposed analytical procedure is well suited for monitoring carbohydrate-modified proteins in cereal products and their end foodstuff products.

This work was supported by the Czech Science Foundation (grant no. P503/12/P395), and by institutional support RVO 68081715 of Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, v.v.i.