Degradation of Epitope Peptides of Wheat Gliadin and Glutenin for Atopic Dermatitis by Crude Proteases from Germinated Wheat Seeds

Abstract

Wheat gliadin and glutenin epitopes for atopic dermatitis were degraded by crude proteases from germinated wheat seeds (PGW). PGW contained cysteine and serine protease activities and hydrolyzed gliadin epitope peptide, PQQPF, at both pH 4.5 and 7.5. The other gliadin epitope peptide, QQPFP, and the overlapped peptide of the two epitopes, PQQPFP, were fully hydrolyzed by PGW at pH 7.5, but were weakly hydrolyzed at pH 4.5. PGW also hydrolyzed the glutenin epitope peptide, QQQPP, at pH 7.5 but only partially at pH 4.5. A 16-mer peptide, CSQQQQPPFSQQQPPF (Glu-16), which incorporated this glutenin epitope twice, was also hydrolyzed by PGW at pH 4.5. Glu-16 was degraded by PGW into QQPP, QQQPP, QQPPF and QQQPPF, as confirmed by mass spectrometry.