MAPPING OF CYCLOSPORINE-A BINDING-SITES IN CYCLOPHILIN-A BY USING SYNTHETIC PEPTIDES

In order to map cyclosporin A (CsA) binding sites of cyclophilin (CyP) , we synthesized the complete set of overlapping 157 octapeptides corr esponding to human CyP A using the multi-pin peptide synthesis system. The pin-coupled synthetic octapeptides were examined in terms of bind ing ability to CsA by a modification of the enzyme-linked immunosorben t assay. Significant binding of CsA was detected with 35 synthetic N-a lpha-acetylated octapeptides possessing the N-terminal amino acids cor responding to the residues in positions 24-26, 42-44, 69-73, 75, 76, 8 9-91, 102, 116, 124-131, 144-151 and 152 in human CyP A, respectively. Other eight octapeptides showed moderate CsA binding activity. The di stinct binding of octapeptides covering the C-terminal region of the C yP A was particularly significant. These data are to be compared with the information provided by X-ray and NMR studies on the CsA binding s ites and furnish thus a test of the reported method. The present study also gave added insight into the CsA interaction sites of CyP.