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Animal Source Foods
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Egg is one of the most important allergens in childhood feeding, and egg allergy can pose quality of life concerns (124). Most of the allergenic egg proteins are found in egg white, including ovomucoid, ovalbumin, ovotransferrin, and lysozyme. Although ovalbumin is the most abundant protein comprising hen’s egg white, ovomucoid has been shown to be the dominant allergen in egg. Egg allergy is closely associated with atopic dermatitis and was found to be present in about two-thirds of children (124). Processed foods containing egg such as cookies must signal its presence to consumers on the labels.
The Modification of Lysine
Published in Roger L. Lundblad, Chemical Reagents for Protein Modification, 2020
In another study, the reversible reductive alkylation of proteins has been examined.106 Both glycolaldehyde and acetol will react with the primary amino groups in proteins to yield derivatives which can be cleaved with periodate under mild basic condition to yield the free amine. Figure 33 shows the distribution of reaction products of lysine and glycolaldehyde as a function of pH with either sodium borohydride (A) or sodium cyanoborohydride (B) as the reducing agent. It is apparent that sodium cyanoborohydride is much more effective in the range of pH 6.0 to pH 8.0 while sodium borohydride is more effective under more alkaline conditions. Treatment of 30.0 mg lysozyme in 6.0 ml 0.2 M sodium borate, pH 9.0, with 60 mg glycoladehyde and 10 mg sodium borohydride at ambient temperature resulted in 60% 2-hydroxyethylation. Treatment of 20 mg ovomucoid in 2.0 ml 0.2 M sodium borate, pH 9.0 with 10% acetol and 30 mg sodium borohydride (added in portions) resulted in 55% hydroxyisopropylation. In both situations, the reaction was terminated by adjustment of the pH to 5 with glacial acetic acid. The extent of modification was determined either by titration with trinitrobenzenesulfonic acid and/or by amino acid analysis after acid hydrolysis. Periodate oxidation could be accomplished with 0.015 M sodium periodate at pH 7.9 for 30 min at ambient temperature.
Food allergens
Published in Richard F. Lockey, Dennis K. Ledford, Allergens and Allergen Immunotherapy, 2020
Several studies have identified the major chicken egg allergens [27,28]. Ovomucoid (Gal d 1), a glycoprotein with a molecular weight of 28 kDa and an acidic isoelectric point, is the major egg allergen. In a study of 18 children with egg allergy, ovomucoid was a more potent allergen than purified ovalbumin as determined by skin prick and in vitro specific IgE tests [29]. While previous studies indicated that ovalbumin was the major egg allergen, this work demonstrated ovomucoid contamination of the ovalbumin accounted for the discrepancy. Ovalbumin (Gal d 2) is a monomeric phosphoglycoprotein with a molecular weight of 43–45 kDa and an acidic isoelectric point. Purified ovalbumin has three primary variants, A1, A2, and A3. It is difficult to determine the exact role of Gal d 2 because of ovomucoid contamination of ovalbumin [29]. Ovotransferrin (Gal d 3), or conalbumin, has a molecular weight of 78 kDa, an acidic isoelectric point, and antimicrobial activity and iron-binding properties. Lysozyme (Gal d 4) is a lower molecular weight allergen (14.3 kDa) that in some studies appears to be a major allergen but in other studies is a minor allergen. Other minor allergens in eggs include serum albumin (Gal d 5), YGP42 (Gal d 6), myosin light chain 1f (Gal d 7), α-parvalbumin (Gal d 8), β-enolase (Gal d 9), and aldolase (Gal d 10). The carbohydrate portion of the glycoproteins in eggs, particularly in ovomucoid, does not play a primary role in specific IgE binding.
Food allergy severity predictions based on cellular in vitro tests
Published in Expert Review of Molecular Diagnostics, 2020
Betul Buyuktiryaki, Alexandra F. Santos
The main allergens of egg are ovomucoid (Gal d 1), ovalbumin (Gal d 2), ovotransferrin/conalbumin (Gal d 3), and lysozyme (Gal d 4). Ovomucoid is an immunodominant allergen owing to its stable structure to heat and proteolysis [63] and has been shown to predict clinic reactivity to baked eggThe major allergens of. However, neither ovomucoid nor the other egg allergen components were effective in predicting the severity of reactions to egg [79]. In Japan, 156 children aged 0–6 years from 11 centers underwent OFC to boiled egg, and, based on the outcome, probability curves depicted ovomucoid sIgE in relation to the severity of reactions [80]. The curve of predicted probabilities showed that the ovomucoid sIgE of 22.4 kU/L had a 95% probability for predicting any symptoms, and 3.8 kU/L had a 5% probability for predicting reactions greater than grade 3. The authors suggested 5% probability curve for severe reactions might help clinicians to make decisions about indications and protocol of OFC.
Allergen immunotherapy for food allergy from the Asian perspective: key challenges and opportunities
Published in Expert Review of Clinical Immunology, 2019
Agnes Sze Yin Leung, Nicki Yat Hin Leung, Christine Yee Yan Wai, Ting Fan Leung, Gary Wing Kin Wong
Similar to wheat OIT, egg OIT is also associated with frequent AEs during the treatment course. All six subjects experienced AE in the study by Itoh et al. [120] while the other study indicated those receiving OIT have a much higher odds ratio (37.4) to experience an AE compared to the control group. Safety issue is thus a major challenge in egg OIT and most studies dedicated to develop a safer protocol in OIT, such as the intermittent regimen reported by Sudo et al. [121]. Hypoallergenic heated and ovomucoid-reduced egg white [136] and a low-dose regimen [137] have also been used in egg OIT trials, but the clinical efficacies are modest (~50% successful desensitization) and thus requires further investigation.
Oral Immunotherapy in Patients with IgE Mediated Reactions to Egg White: A Clinical Trial Study
Published in Immunological Investigations, 2022
Vahid Ghobadi Dana, Morteza fallahpour, Raheleh Shokouhi Shoormasti, Mohammad Nabavi, Mohammad Hassan Bemanian, Mohsen Fateh, Zeinab Zaker, Mehdi Torabizadeh, Seyed Ali Aghapour, Saba Arshi
Gal d1-5 have been identified as five main allergenic molecules of hen egg (Gallus domesticus). Among these allergens, four proteins belong to egg white including ovomucoid (Gal d 1), ovalbumin (Gal d 2), ovotransferrin (Gal d 3) lysozyme (Gal d 4) (Matricardi et al. 2016). Despite the high concentration of ovalbumin (OVA) in the egg white, ovomucoid is regarded as the dominant allergen and unlike ovalbumin, it is a heat-stable allergen (Bartnikas et al. 2013).