Fusion and Expression of
the Genes Encoding Murine-Human Chimeric Heavy Chain to Carcinoembryonic
Antigen with Core-streptavidin Gene
YANG Wei-Dong1,2, LI Biao1, ZHU Cheng-Mo1, LIAO Wen-Tao2, YANG Guan-Zhen2, WU Xiang-Fu2*
( 1Rui Jin Hospital, Shanghai
No.2 Medical University, Shanghai 200025, China；2Shanghai Institute of
Biochemistry, the Chinese Academy of Science, Shanghai 200031, China )
Abstract
In order
to reduce the human anti-murine antibody (HAMA) in radioimmunotherapy, the gene
encoding the heavy chain variable region (VH) of the murine monoclonal
antibody with high specificity and affinity to carcinoembryonic antigen was
fused to the human Cγ3 gene to construct the murine-human
chimeric heavy chain antibody gene, then was linked to core-streptavidin which
can specifically bind to biotin, facilitating its purification and radioisotope
labeling. The fusion gene was expressed in E.coli at high level,
accounting for 24% of the total bacteria protein, and was characterized by
SDS-PAGE and Western-blots. When using RIA the content of inclusion bodies was
denatured and followed by renaturation, it was shown by using RIA to possess
ability to bind to its specific antigen of CEA. Using horseradish peroxidase
(HRP) labeled biotin as antibody in Western-blots, one band of 70 kD only was
detected, demonstrating the fusion protein not only had the ability to bind
CEA, but also could bind biotin specifically.
Key Words carcinoembryonic antigen； chimeric heavy chain
antibody；
core-streptavidin； geng expression
Received: July 14,
1999 Accepted: September 9, 1999
* Corresponding author: Tel, 86-21-64374430-292; Fax, 86-21-64338357; e-mail, [email protected]1,2