Designed heterodimerizing leucine zippers with a ranger of pIs and stabilities up to 10(-15) M

Protein Sci. 2001 Mar;10(3):649-55. doi: 10.1110/ps.39401.


We have designed a heterodimerizing leucine zipper system to target a radionuclide to prelocalized noninternalizing tumor-specific antibodies. The modular nature of the leucine zipper allows us to iteratively use design rules to achieve specific homodimer and heterodimer affinities. We present circular-dichroism thermal denaturation measurements on four pairs of heterodimerizing leucine zippers. These peptides are 47 amino acids long and contain four or five pairs of electrostatically attractive g <--> e' (i, i' +5) interhelical heterodimeric interactions. The most stable heterodimer consists of an acidic leucine zipper and a basic leucine zipper that melt as homodimers in the micro (T(m) = 28 degrees C) or nanomolar (T(m) = 40 degrees C) range, respectively, but heterodimerize with a T(m) >90 degrees C, calculated to represent femtamolar affinities. Modifications to this pair of acidic and basic zippers, designed to destabilize homodimerization, resulted in peptides that are unstructured monomers at 4 microM and 6 degrees C but that heterodimerize with a T(m) = 74 degrees C or K(d(37)) = 1.1 x 10(-11) M. A third heterodimerizing pair was designed to have a more neutral isoelectric focusing point (pI) and formed a heterodimer with T(m) = 73 degrees C. We can tailor this heterodimerizing system to achieve pharmacokinetics aimed at optimizing targeted killing of cancer cells.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Antineoplastic Agents / chemistry
  • Circular Dichroism
  • Dimerization
  • Drug Design
  • Drug Stability
  • Isoelectric Point
  • Leucine Zippers / genetics*
  • Molecular Sequence Data
  • Peptides / genetics*
  • Peptides / metabolism
  • Protein Denaturation
  • Protein Splicing / genetics
  • Radiation Chimera / metabolism
  • Radioimmunotherapy
  • Static Electricity
  • Thermodynamics


  • Antineoplastic Agents
  • Peptides