AFFINITY MATURED CRIg VARIANTS

摘要

PROBLEM TO BE SOLVED: To provide CRIg variants having increased binding affinity to C3b and retaining selective binding to C3b over C3.SOLUTION: A CRIg variant comprises an amino acid substitution in a region selected from among E8-K15, R41-T47, S54-Q64, E85-Q99 and Q105-K111 of a specific amino acid sequence. A DNA fragment encoding CRIg is ligated into a phagemid vector (p3DvlzPDZ-gD) as a wild type control and a template for designing CRIg variants. Then, templates with the TAA stop codon at each residue targeted for randomization are prepared from CJ239 Escherichia coli cells. A soft randomization strategy is used for CRIg variants selection to design libraries. The CRIg variant uses modified competitive phage ELISA in order to estimate binding affinity.