Investigation of Protein and Epitope Characteristics of Oats and Its Implications for Celiac Disease

Gyöngyvér Gell; Zsuzsanna Bugyi; Christakis George Florides; Zsófia Birinyi; Dalma Réder; Zsuzsanna Szegő; Edina Mucsi; Eszter Schall; Katalin Ács; Bernadett Langó; Szandra Purgel; Katalin Simon; Balázs Varga; Gyula Vida; Ottó Veisz; Sándor Tömösközi; Ferenc Békés

doi:10.3389/fnut.2021.702352

Investigation of Protein and Epitope Characteristics of Oats and Its Implications for Celiac Disease

Front Nutr. 2021 Sep 29:8:702352. doi: 10.3389/fnut.2021.702352. eCollection 2021.

Authors

Gyöngyvér Gell^{1

2}, Zsuzsanna Bugyi², Christakis George Florides³, Zsófia Birinyi¹, Dalma Réder¹, Zsuzsanna Szegő², Edina Mucsi², Eszter Schall², Katalin Ács⁴, Bernadett Langó⁴, Szandra Purgel⁴, Katalin Simon⁵, Balázs Varga⁶, Gyula Vida⁶, Ottó Veisz⁶, Sándor Tömösközi², Ferenc Békés⁷

Affiliations

¹ Department of Biological Resources, Agricultural Institute, Centre for Agricultural Research, EötvösLoránd Research Network, Martonvásár, Hungary.
² Department of Applied Biotechnology and Food Science, Research Group of Cereal Science and Food Quality, Budapest University of Technology and Economics, Budapest, Hungary.
³ Murdoch University, College of Science, Health, Engineering and Education, Perth, WA, Australia.
⁴ Cereal Research Non-Profit Ltd., Szeged, Hungary.
⁵ First Pest Mill and Bakery Ltd., Budapest, Hungary.
⁶ Cereal Breeding Department, Agricultural Institute, Centre for Agricultural Research, EötvösLoránd Research Network, Martonvásár, Hungary.
⁷ FBFD PTY Ltd., Sydney, NSW, Australia.

Abstract

The use of pure oats (oats cultivated with special care to avoid gluten contamination from wheat, rye, and barley) in the gluten-free diet (GFD) represents important nutritional benefits for the celiac consumer. However, emerging evidence suggests that some oat cultivars may contain wheat gliadin analog polypeptides. Consequently, it is necessary to screen oats in terms of protein and epitope composition to be able to select safe varieties for gluten-free applications. The overall aim of our study is to investigate the variability of oat protein composition directly related to health-related and techno-functional properties. Elements of an oat sample population representing 162 cultivated varieties from 20 countries and the protein composition of resulting samples have been characterized. Size distribution of the total protein extracts has been analyzed by size exclusion-high performance liquid chromatography (SE-HPLC) while the 70% ethanol-extracted proteins were analyzed by RP-HPLC. Protein extracts separated into three main groups of fractions on the SE-HPLC column: polymeric proteins, avenins (both containing three subgroups based on their size), and soluble proteins, representing respectively 68.79-86.60, 8.86-27.72, and 2.89-11.85% of the total protein content. The ratio of polymeric to monomeric proteins varied between 1.37 and 3.73. Seventy-six reversed phase-HPLC-separated peaks have been differentiated from the ethanol extractable proteins of the entire population. Their distribution among the cultivars varied significantly, 6-23 peaks per cultivar. The number of appearances of peaks also showed large variation: one peak has been found in 107 samples, while 15 peaks have been identified, which appeared in less than five cultivars. An estimation method for ranking the avenin-epitope content of the samples has been developed by using MS spectrometric data of collected RP-HPLC peaks and bioinformatics methods. Using ELISA methodology with the R5 antibody, a high number of the investigated samples were found to be contaminated with wheat, barley, or rye.

Keywords: ELISA; HPLC; avenin; celiac disease; epitope prediction; oat.