SYNTHETIC PEPTIDES WITH BINDING SPECIFICITY FOR ANTIPHOSPHOLIPID ANTIBODIES.

David S. Jones, Paul A. Barstad, Merle S. Hayag, Michael K. Pabarcus, Travis P. Remarchuk, Edward J. Victoria, and Steve C. Yabut.

La Jolla Pharmaceutical Company, San Diego, CA 92121

Antiphospholipid antibodies (aPL) from patients with recurrent stroke were tested for their ability to bind synthetic disulfide cyclized peptides with sequences derived by screening phage libraries. A competitive binding assay was developed, and peptides were rank ordered by their ability to compete for aPL with a tetrameric peptide coated on polystyrene. Peptide binding was affected by invariant amino acids which normally flank the N terminus of the random phage insert. The immunoreactivity of a strong binding peptide was enhanced significantly by replacing a proline with an a-methyl proline. For one patient, one peptide bound all of the aPL activity

Presented at the Western Biotech Conference, Oct. 18-21, 1995, San Diego, CA.