SYNTHESIS OF A RADIOIODINATED PHOTOREACTIVE MAGE-1 PEPTIDE DERIVATIVEAND PHOTOAFFINITY-LABELING OF CELL-ASSOCIATED HUMAN-LEUKOCYTE ANTIGEN-A1 MOLECULES

The synthesis of a photoreactive derivative of the human leukocyte ant igen-A1 (HLA-A1)-restricted MAGE-1 peptide 161-169 (EADPTGHSY) is desc ribed, Using conventional automated solid-phase peptide synthesis, a p hotoreactive derivative of this peptide was synthesized by replacing h istidine-167 with photoreactive N-beta-4-azidosalicyloyl-L-2,3-diamino propionic acid, The C-terminal tyrosine was incorporated as phosphotyr osine, This peptide derivative was radioiodinated in the presence of c hloramine T. This iodination took place selectively at the photoreacti ve group, because the phosphate ester prevented tyrosine iodination. F ollowing dephosphorylation with alkaline phosphatase and chromatograph ic purification, the radiolabeled peptide derivative was incubated wit h cells expressing HLA-A1 or other HLA molecules, Photoactivation resu lted in efficient photo affinity labeling of HLA-A1, Other HLA molecul es or other cellular components were not detectably labeled, This labe ling was inhibited by HLA-A1 but not by HLA-A2-binding peptides, This synthesis is generally applicable and can also be adapted to the synth esis of well-defined radiolabeled nonphotoreactive peptide derivatives . (C) 1995 Academic Press, Inc.