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.