Co-60 gamma irradiation induced ovalbumin-glucose glycation and allergenicity reduction revealed by high-resolution mass spectrometry and ELISA assay

Ovalbumin (OVA)-glucose mixture was treated with Co-60 irradiation at 0-25 kGy, and effects of irradiation on the glycation and allergenicity of OVA were investigated. Irradiation induced glycation between OVA and glucose, reflected in the significant increase of glycation sites from 3 to 14. Interestingly, OVA irradiated at 25 kGy had three new glycated peptides (568.782+, 739.382+ and 509.752+). The degree of substitution per peptide molecule (DSP) of glycated peptides exhibited different trends with increasing irradiation dose. Particularly, glycated peptides 17-26, 55-60, 263-267 and 368-375 showed markedly decreased DSP values after irradiation at 20 and 25 kGy, which could be caused by the generation of Maillard reaction products (MRPs). MS/MS spectra suggested that neutral loss occurred in glycated arginine, whose structure was similar to MRPs. The IgG- and IgEbinding abilities of OVA significantly decreased with increasing irradiation dose, indicating that the protein allergenicity was reduced.