Disulfide bond bridged divalent antibody-toxin, (Fab-PE38fl)2, with the toxin PE38 fused to the light chain

Jae Seon Won, Mu Hyeon Choe

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


B3 antibody specifically binds the LewisY-related carbohydrate antigen of many carcinomas, and it is used as a model antibody in this study. In a previous study, the Fab fragment of the antibody was fused to a 38 kDa truncated form of Pseudomonas exotoxin A, PE38, to make Fab-PE38, where PE38 is fused to the Fd fragment of the Fab domain. This parent monomer molecule, Fab-PE38, had no cysteine in the hinge region, and it could not make a disulfide bond to form a disulfide bond bridged homodimer [7]. In this study, we constructed three different kinds of divalent Fab-toxin fusion homodimers where the toxin is fused to the light chain of Fab, (Fab-PE38fl)2. In addition to the PE38 toxin fused to the light chain, these three molecules have different hinge sequences h1, h2, and h3 making Fabh1-, Fabh2-, and Fabh3-PE38fl monomers, respectively. These hinges contain only one cysteine on different positions of the hinge sequence. The disulfide bond between the hinge region of two monomers forms homodimers (Fabh1-PE38fl)2, (Fabh2-PE38fl)2, and (Fabh3-PE38fl)2. The refolding yields of these dimers were 5 - 16-fold higher than a previously constructed dimer where the PE38 was fused to the Fd fragment (Fabh1-PE38)2 [8]. Our data suggest that the steric repulsion between the two PE38s in (Fabh1-PE38)2 during disulfide bridge formation is relieved by fusing it at the end of the light chain. The best cytotoxicity value of these dimers showed about 2.5-fold higher on an MCF7 cell line than that of the monovalent reference molecule in ng/ml scale, which is 15-fold higher in pM scale.

Original languageEnglish
Pages (from-to)1475-1481
Number of pages7
JournalJournal of microbiology and biotechnology
Issue number8
Publication statusPublished - 2008 Aug 28


  • Antibody refolding
  • Cytotoxicity
  • Divalent antibody-toxin
  • Homodimer
  • Light chain-toxin fusion
  • Pseudomonas exotoxin A

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology


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