A diabody that dissociates to monomer forms at low concentration: effects on binding activity and tumor targeting

Biochem Biophys Res Commun. 2005 Feb 25;327(4):999-1005. doi: 10.1016/j.bbrc.2004.12.114.


A human scFv, 15-9, was selected from a phage display library for binding to murine laminin-1. A diabody was made from the scFv by shortening the linker from 15 to 5 amino acids between the VH and VL sequence. Radioiodinated scFv and diabody were analyzed for size, binding to laminin, and biodistribution in tumor bearing mice. Diabody preparations at concentrations greater than 10 nM were largely dimer forms (approximately 60 kDa) as judged by gel filtration, but diluted diabody was eluted as a monomer (approximately 30 kDa). At low concentrations the radiolabeled diabody did not bind well to laminin. The (125)I diabody had significantly lower accumulation in tumors than did the scFv when injected at lower concentrations. These data indicate that the diabody dimer dissociates at concentrations of about 10nM resulting in monomers with no binding activity for laminin and poor tumor homing properties.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Antibody Affinity / immunology*
  • Antibody Specificity / immunology
  • Chromatography, Gel
  • Female
  • Immunoglobulin Variable Region / analysis
  • Immunoglobulin Variable Region / chemistry*
  • Immunoglobulin Variable Region / genetics
  • Immunoglobulin Variable Region / immunology*
  • Iodine Radioisotopes
  • Laminin / immunology
  • Laminin / metabolism
  • Mice
  • Mice, SCID
  • Neoplasm Transplantation
  • Neoplasms / immunology*
  • Protein Engineering*
  • Protein Subunits / chemistry*
  • Protein Subunits / genetics
  • Protein Subunits / immunology
  • Protein Subunits / pharmacokinetics
  • Tissue Distribution


  • Immunoglobulin Variable Region
  • Iodine Radioisotopes
  • Laminin
  • Protein Subunits
  • laminin 1