Degenerate binding of tyrosinase peptides to MHC II Ad/Ed molecules.

Recently we defined the tyrosinase233-247IPYWDWRDAEKCDIC peptide as the pentadecamer sequence hosting the linear determinant of the anti-tyrosinase MAb T311. In order to understand the molecular features that render epitopic the amino acid tyrosinase233-247 sequence, we 1) analyzed the MHC II affinity of the tyrosinase233-247IPYWDWRDAEKCDIC peptide using RankPep as a binding prediction program, and 2) experimentally verified the actual peptide-MHC II interaction by carrying out peptide electrophoretic mobility shift assays. Nine random tyrosinase peptides were used as controls. Under the conditions used in this study, it was found that all of the ten tyrosinase peptides were capable of binding to Ad/Ed molecules in the gel-shift binding assay. Moreover, there was no correlation between the theoretical predicted Ad/Ed affinity and the experimental actual peptide binding. We conclude that Ad/Ed binding potential appears influential in the defining of tyrosinase233-247IPYWDWRDAEKCDIC peptide epitopicity.