Binding of Cu(II) or Zn(II) in a de novo designed triple-stranded alpha-helical coiled-coil toward a prototype for a metalloenzyme.
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.
Kiyokawa
T
T
Department of Applied Biology, Kyoto Institute of Technology, Matugasaki, Sakyou-ku, Kyoto 606 8585, Japan.
Kanaori
K
K
Tajima
K
K
Koike
M
M
Mizuno
T
T
Oku
J-I
JI
Tanaka
T
T
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
D004798:Enzymes; D008667:Metalloproteins; D010455:Peptides; D003300:Copper; D015032:Zinc