title: Binding of Cu(II) or Zn(II) in a de novo designed triple-stranded alpha-helical coiled-coil toward a prototype for a metalloenzyme.
abstract: We previously reported the IZ-3adH peptide, which formed a triple-stranded coiled-coil after binding Ni(II), Cu(II), or Zn(II). In this paper, we report the peptide, IZ-3aH, having a new metal binding specificity. The IZ-3aH peptide was found to bind Cu(II) and Zn(II) and form a triple-stranded coiled-coil. However, it did not bind Ni(II). Metal ion titrations monitored by circular dichroism revealed that the dissociation constants, K(d) were 9 microm for Zn(II) and 10 microm for Cu(II). The bound Cu(II) ion has a planar tetragonal geometry, where the coordination positions are three nitrogens of the His residues and one H(2)O.
authors.affiliation: Department of Applied Biology, Kyoto Institute of Technology, Matugasaki, Sakyou-ku, Kyoto 606 8585, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kiyokawa
authors.forename: K
authors.initials: K
authors.lastname: Kanaori
authors.forename: K
authors.initials: K
authors.lastname: Tajima
authors.forename: M
authors.initials: M
authors.lastname: Koike
authors.forename: T
authors.initials: T
authors.lastname: Mizuno
authors.forename: J-I
authors.initials: JI
authors.lastname: Oku
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry* / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D004798:Enzymes / Q000737:chemistry* / Q000378:metabolism; D008667:Metalloproteins / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D015202:Protein Engineering; D017433:Protein Structure, Secondary; D013379:Substrate Specificity; D015032:Zinc / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004798:Enzymes; D008667:Metalloproteins; D010455:Peptides; D003300:Copper; D015032:Zinc