title: Designed heterodimerizing leucine zippers with a ranger of pIs and stabilities up to 10(-15) M.
abstract: 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.
authors.affiliation: Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Moll
authors.forename: S B
authors.initials: SB
authors.lastname: Ruvinov
authors.forename: I
authors.initials: I
authors.lastname: Pastan
authors.forename: C
authors.initials: C
authors.lastname: Vinson
mesh_terms: D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000737:chemistry; D002942:Circular Dichroism; D019281:Dimerization; D015195:Drug Design; D004355:Drug Stability; D007526:Isoelectric Point; D016350:Leucine Zippers / Q000235:genetics*; D008969:Molecular Sequence Data; D010455:Peptides / Q000235:genetics* / Q000378:metabolism; D011489:Protein Denaturation; D019154:Protein Splicing / Q000235:genetics; D011828:Radiation Chimera / Q000378:metabolism; D016499:Radioimmunotherapy; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D000970:Antineoplastic Agents; D010455:Peptides