Affinity Improvement of Antibody-Avidin Fusion Proteins for Biotin

Cho, Mi Young; Kim, Hae Jung; Cho, Hyun Mi; Shin, Seung Uon

Abstract

To generate drug delivery vector to locales in the body, genetic engineering and expression techniques have been used to produce antibody avidin fusion proteins. Chicken avidin has been fused to mouse-human chimeric IgG3 immediately after the hinge with a flexible linker (H-Flex-Av) and at the end of CH2 (CH2-Av). Fusion heavy chains were expressed with the expected molecular weight, assembled as H2L2 forms with a co-expressed light chain, and were secreted. The expression level of H- Flex-Av was 1~10 ug/ml/10(8)/24 hrs, but that of C2-Av was a very little (0.08~0.9 ug/ ml/10(8)/24 hrs). The resulting H-Flex-Av and CH2-Av fusion proteins continued to bind antigen dansyl and also bound biotinylated bovine serum albumin; both H-Flex-Av and CH2-Av had shown to retain 3-4 times higher relative affinity than that of CH3-Av in ELISA. Importantly the fact that both avidin fusion proteins had a higher relative affinity suggests that these avidin fusion proteins can be effectively used to deliver biotinylated ligands such as drugs and peptides to a certain locale, such as the brain.