COMBINATORIAL SEARCH FOR DIAGNOSTIC AGENTS - LYME ANTIBODY H9724 AS AN EXAMPLE

Two peptide libraries, Ac-MXXXXXBBRM and Ac-VXXYXXBBRM, were construct ed on TentaGel solid support to search for ligands that bind tightly w ith the H9724 Lyme antibody. By using an on-bead ELISA, approximately 120 ligands were selected as candidates for further study. Matrix-assi sted laser desorption ionization mass spectrometry analysis of the can didate ligands indicated a high rate of occurrence of certain amino ac ids at the randomized positions. On the basis of the initial screening results, a small library was designed and iteratively synthesis. Subs equent library screenings led to the identification of four peptides, Ac-PQEEGX-NH2 (X = R, K, A, D), that showed specific affinity to the a ntibody. This combination of solid-phase screening and iterative synth esis is an effective strategy for rapid identification of ligands that bind tightly with disease-specific antibodies and should be applicabl e, at least In principle, to other ligand-receptor systems, This combi natorial library approach can also be a useful tool for the discovery of novel diagnostic agents.