Cor a 14, the allergenic 2S albumin from hazelnut, is highly thermostable and resistant to gastrointestinal digestion

Abstract

ScopeAllergens from nuts frequently induce severe allergic reactions in sensitive individuals. The aim of this study was to elucidate the physicochemical characteristics of natural Cor a 14, the 2S albumin from hazelnut.Methods and resultsCor a 14 was purified from raw hazelnuts using a combination of precipitation and chromatographic techniques. The protein was analyzed using gel electrophoresis, MS, and far‐UV circular dichroism (CD) analyses. The immunoglobulin E (IgE) binding of native, heat‐treated, and in vitro digested Cor a 14 was studied. We identified two different Cor a 14 isoforms and showed microclipping at the C‐terminus. CD spectra at room temperature showed the typical characteristics of 2S albumins, and temperatures of more than 80°C were required to start unfolding of Cor a 14 demonstrating its high stability to heat treatment. In vitro digestion experiments revealed that Cor a 14 is resistant to proteolytic degradation. Native and heat‐treated protein was recognized by sera from hazelnut allergic patients. However, denaturation of the allergen led to significantly reduced IgE binding.ConclusionWe identified two different isoforms of Cor a 14 displaying high stability under heating and gastric and duodenal conditions. Data from IgE‐binding experiments revealed the existence of both, linear and conformational epitopes.

A comprehensive analysis of the allergenicity and IgE epitopes of myosinogen allergens in Scylla paramamosain

“…The purified allergens were detected by SDS-PAGE and confirmed by the immunoblotting with the specific IgG polyclonal antibodies (pAb) prepared previously ( Figure 2). 5,9,11 Figure 1B describes the prevalence of crab myosinogen allergens among the 398 AC subjects, and the proportions of subjects allergic to AK, SCP, TIM, and FLN c were 24.87% (n = 99), 18.34% (n = 73), 19.10% (n = 76), and 25.13%…”

“…Food allergens contain both conformational and linear epitopes. Linear epitopes are relevant for immunoreactivity in gastrointestinal food allergies . Peptide micro‐arrays provide a tool for mapping linear IgE epitopes .…”

“…Linear epitopes are relevant for immunoreactivity in gastrointestinal food allergies. 19,20 Peptide micro-arrays provide a tool for mapping linear IgE epitopes. 21 Conformational epitopes can be influenced by the microenvironment of a folded protein, so its identification requires more elaborated methods, and the most precise way to identify a conformational epitope is to determine the crystal structure of an antigen-antibody complex.…”

Gastrointestinal digestion of hazelnut allergens on molecular level: Elucidation of degradation kinetics and resistant immunoactive peptides using mass spectrometry

“…A high stability against in vitro digestion has been described for 2S albumins and LTPs from several allergenic foods [23,25,49,50]. Concerning the digestion of hazelnut allergens, Vieths et al also observed a high resistance of the prolamin fraction, with retained IgE binding for proteins in the prolamin molecular size range [20], and Pfeifer et al recently reported that isolated Cor a 14 withstood simulated gastric and intestinal digestion [51]. Differently to these former studies, Cor a 14 and Cor a 8 were shown to be degraded by intestinal enzymes in our model system, a deviation that might again be explained by our model system, which more closely reflects the physiological situation, and by subjecting the whole food matrix towards digestion (instead of isolated proteins), which has been discussed as an influence on single protein digestibility in another recent study [26].…”

Current (Food) Allergenic Risk Assessment: Is It Fit for Novel Foods? Status Quo and Identification of Gaps

“…Both, far and near CD spectra have been useful in monitoring thermal stability of food allergens, i.e. thermal stability of Cor a 14, the 2S albumin from hazelnut . The effects of high‐pressure/temperature treatment and pulsed electric field treatment on peanut Ara h 2 and 6 and apple Mal d 3 and 1b were examined by CD spectroscopy and the results showed that novel processing technologies had little effect on the allergen structure.…”