earticle

영어

Previously we reported novel target-specifuc binding proteins of modest potency that was derived from a synthetic kringle domain(KD) library on the yeast cell surface. We isolated KD variants that bind to anti-cancer target proteins, such as human death receptor (DR) 5. We selected two KD variants (KD506 and KD548) which have tumoricidal activity. The anti-DR5 KD variants (KD506 and KD548) function as agonists to induce apoptotic cell death in several cancer cell lines in vitro. However, the selected KD variants have low affinity (KD = ~10-7 M) compared with TRAIL and other anti-DR5 antibodies. For affinity improvement, we engineered loops of KD variants particularly loop5 and loop6 which are selected by loop mapping by yeast surface display. Using yeast surface display (YSD) system, libraries were constructed to minimize the number of non-viable structures by rational design of nucleotide mixtures which bias for the wild-type (parent mutant) residues. The high affinity mutants of the KD variants were isolated by using MACS and FACS systems.