Functional analysis of the antigenic structure of a minor T cell determinant from pigeon cytochrome C. Evidence against an alpha-helical conformation.

摘要: A minor T cell determinant from pigeon cytochrome c, composed of residues 43 to 58 (p43-58), was synthesized along with a series 48 analogs containing amino or carboxyl-terminal deletions single acid substitutions. These peptides were analyzed functionally for their ability elicit unique populations on immunization C57BL/10 mice and stimulate degenerate clone capable recognizing p43-58 in association two different Ia molecules, beta b:A alpha b d:A d. experiments allowed us identify the that are critical activation. Residues 50 52 had dominant influence specificity, 47, 48, 49, 51, 53 weak effects. 46 54 hardly recognized by TCR at all, but appeared potency interacting molecule. Finally, substitutions positions 55 no effect, removal these reduced peptide, suggesting contribution peptide backbone this part molecule during An analysis spatial relationship epitopic agretopic suggests does not assume pure alpha-helical secondary structure when bound