Abstract
Egg white proteins are one of the major allergens. The objective of this study was to investigate the effect of <i>Aspergillus oryzae</i> cultivation on IgE binding ability of egg white proteins. Effect of <i>A. oryzae</i> on egg white proteins was determined using ninhydrin method, SDS-PAGE, ELISA, fluorescence FITC labeling, MALDI-TOF-MS and LC-MS/MS analysis. Adding mycelium of <i>A. oryzae</i> ATCC 1011 and 16868 substantially reduced the IgE binding ability of acidified egg white after 24 h incubation. The binding capacity of egg white proteins to IgE in plasma from four egg allergy patients was almost completely lost after incubation with mycelium of ATCC 16868. Results from SDS-PAGE, free amino acid analysis, MALDI-TOF-MS and LC-MS/MS indicated that there was no substantial protein degradation during incubation. Therefore, the reduction of IgE binding ability of egg white proteins during <i>A. oryzae</i> treatment was probably due to a loss of ~1700 Da mass including a fragment of the ovomucoid N terminus.
Highlights
Egg whites contain four major egg allergens, ovomucoid (Gal d 1, 11%), ovalbumin (Gal d 2, 54%), ovotransferrin (Gal d 3, 12%) and lysozyme (Gal d 4, 3.4%)[1]
Β-mercaptoethanol, acetone, bovine serum albumin (BSA), cysteine, fluorescein isothiocyanate (FITC), goat-anti-human IgE conjugated with alkaline phosphate, p-nitrophenyl phosphate and Tween-80 were purchased from Sigma-Aldrich
The results show that mycelium of A. oryzae is more effective than conidiospores in reducing IgE binding ability of egg whites
Summary
Egg whites contain four major egg allergens, ovomucoid (Gal d 1, 11%), ovalbumin (Gal d 2, 54%), ovotransferrin (Gal d 3, 12%) and lysozyme (Gal d 4, 3.4%)[1]. Unlike other egg white proteins, ovomucoid is resistant to heat and digestive enzymes. Most (~60%) egg allergic patients are sensitive to heated egg white, the Received August 27, 2017; accepted January 15, 2018. (Using 34 sera from adults who had egg allergies, Aabin et al.[8] reported that ovotransferrin and ovomucoid had higher IgE binding ability than ovalbumin and lysozyme. The greater IgE binding ability of ovotransferrin and ovomucoid was confirmed by Jacobsen et al.[9] It was estimated that about 35% of egg allergy patients are sensitive to lysozyme[10]
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