USE OF SYNTHETIC PEPTIDE LIBRARIES FOR THE H-2KD BINDING MOTIF IDENTIFICATION

To identify Kd-binding peptides, an approach based on small peptide li braries has been developed. These peptide libraries correspond to all possible single-amino acid variants of a particular Kd-binding peptic- le, SYIPSAEYI, an analog of the Plasmodium berghei 252-260 antigenic p eptide SYIPSAEKI. In the parent sequence, each position is replaced by all the genetically encoded amino acids (except cysteine). The multip le analog syntheses are performed either by the Divide Couple and Reco mbine method or by the Single Resin method and generate mixtures conta ining 19 peptides. The present report deals with the synthesis, the pu rification, the chemical characterization by amino acid analysis and e lectrospray mass spectrometry (ES-MS), and the application of such mix tures in binding tests with a soluble, functionally empty, single-chai n H-2 Kd molecule denoted SC-Kd. For each mixture, bound peptides were eluted and analyzed by sequencing. Since the binding rests were reali zed in noncompetitive conditions, our results show that a much broader set of peptides bind to Kd than expected from previous studies. This may be of practical importance when looking Sol low affinity peptides such as tumor peptides capable of eliciting protective immune response .