Effect of histidine methylation on the recognition of OVA323–336 T-epitope: Synthesis ofN-α-Fmoc-N-τ-methyl-L-histidine and its use for the synthesis of two histidine methylated analogues of OVA323–336

N-α-Fmoc-N-τ-methyl-L-histidine was prepared in three steps fromN-α-Boc-L-histidine by treatment with methyliodine in DMF at−10°C, deprotection of theN-α position in pure TFA and subsequent reprotection by Fmoc-chloroformate in a 5% Na2CO3/dioxane mixture.N-α-Fmoc-N-τ-methyl-L-histidine was then used for the solid-phase synthesis of two analogues of the OVA323–336 T-epitope, methylated on His331 and on His328/331, respectively. These peptides were tested for their ability to activate 3 DO-54.8 T-cell hybridoma when presented by fixed A-20.1.11 antigen presenting cells, and no significant difference was observed in IL-2 production.