Potential allergenicity assessment after bovine apo‐α‐lactalbumin binding to calcium ion

Abstract

Bovine α‐lactalbumin (α‐LA) is recognized as a major milk allergen. Generally, α‐LA in the natural state combines with a calcium ion, however, some studies have shown that calcium ions can binding the other metal binding sites in α‐LA as well. In our study, the optimal condition of calcium ion binding to α‐LA and the change of structure and allergenicity were explored. By optimizing the conditions, the maximum calcium binding amounts of apo‐α‐LA were obtained in a ratio of 1:4. The structure of α‐LA after removal of calcium obviously changed by the spectroscopic detection. For the digestive stability, there was no obvious change in three forms of α‐LA. While the allergenic properties were characterized by IgG/IgE inhibition ELISA and the human basophil KU812 degranulation assay. The results showed that IgG and IgE binding decreased, and the degranulation capacity of basophils weakened. Based on these results, calcium binding to apo‐α‐LA can reduce the potential allergenic properties. Practical applications By optimizing the conditions, bovine apo‐α‐LA can obtain the most calcium binding amount. And calcium binding to apo‐α‐LA can reduce the potential allergenic properties. Compared with α‐LA in the natural state, calcium binding to α‐LA not only can reduce the allergenic properties, but also play a role in calcium supplementation. It might be used to guide the development of hypoallergenic α‐LA and provide a method to reduce the potential allergenic properties of α‐LA.

Identification of peptides sequence and conformation contributed to potential allergenicity of main allergens in yogurts

“…The competitive ELISA assay was also used to detect the IgE binding ability of protein in Figure 5 . IC 50 is the competitive concentration of allergen when antibody binding has been inhibited by 50%, which a high IC 50 value indicates low allergenicity ( 21 ). In the Figure 5A , the calculated IC 50 values of the samples from fresh milk, JA yogurt, JSD yogurt, HS yogurt, HN yogurt, HR yogurt, and GuMi yogurt were gradually increased.…”

“…The IgE binding ability of yogurts was identified by competitive ELISA ( 21 ). Briefly, 1 μg/mL of skim milk in 0.05 M carbonate buffer (pH 9.6) was used to coat a 96-well microtiter plate (100 μL/well) at 4°C overnight.…”

Potential allergenicity and hydrolysis assessment of bovine casein and β‐casein by treatment with lactic acid bacteria

“…The competitive ELISA was used to detect the IgG and IgE‐binding abilities of the hydrolysates. The method was described previously with some modifications (Huang et al, 2020; Meng et al, 2017). It should be noted that 0.5 μg/ml casein or β‐casein was used to coat a 96‐well plate.…”