Investigation of IgE and IgG epitopes on ovomucoid using egg-white allergic patients' sera

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Zhang, Jie Wei
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University of Guelph

Ovomucoid, the major allergen in egg white, contains DI, DII, and DIII-CHO+ or DIII-CHO. There was significantly more IgG binding to DIII and significantly more IgE binding to DIII-CHO than to either DI or DII. The main IgE and IgG epitopes on each domain were linear. The carbohydrate moiety in DIII had a rather inhibiting effect on its IgG binding and no effect on its IgE binding activities. Three IgE epitopes (EE1 and EE2, 159-173; EE3, 179-186) and three IgG epitopes (EG1, 161-167; EG2, 165-174; EG3, 177-183) were identified. The critical amino acids for IgE epitopes were Y\sp161, G\sp162, N\sp163, F\sp167, C\sp168, A\sp170 and/or K\sp185, C\sp186 and for IgG were from K\sp164 to C\sp168 and from T\sp177 to H\sp182. A hydrophobic amino acid group may be more critical for IgE binding to DIII, whereas a hydrophilic amino acid group appears to be more critical for IgG binding.

IgE epitopes, IgG epitopes, ovomucoid, egg-white, allergic patient, sera