2.5 Bioinformatics analysis
To quantify the similarity between αs1-CN and the other CN components, the Property Distance (PD ) value was calculated using the Property-Based Peptide Similarity Index PD for Two Sequences tool (http://Fermi.utmb.edu/ SDAP/sdap_pdi.html).8 In brief, the sequential peptides consisting of ten amino-acids, overlapping by seven (three-offset), in the primary sequence of αs1-CN were applied to the amino-acid sequences of β- and κ-CN. Peptides with PD values lower than 10 indicated significant physicochemical similarities, whereas much higher PDvalues implied unrelated peptides. In addition, to identify the putative cross-reactive peptides, αs1-CN-specific IgE epitopes reported by the previous studies were also applied to the amino acid sequences of αs2-, β-, and κ-CN.