Formation of Artificial Metal-Peptide Assemblies

1
Formation of Artificial
Metal-Peptide Assemblies

• Brandon Young, Mikhail V Tsurkan, and Michael Y
  Ogawa

Department of Chemistry and Center for
Photochemical Sciences, Bowling Green State
University Ohio Science and Engineering
Conference
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Why?

• To Control Metal-directed Protein Folding and
  Assembly
• To Make synthetic metalloenzymes and proteins
  that could be used in organic applications
• Diabetes
• Cystic fibrosis
• Prion disease (Mad Cow)
• Sickle cell
• Utilized for Drug delivery systems
• "nanomachines"

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Solid Phase Peptide Synthesis Scheme
Peptide Synthesizer
AC-QIAALEQKIAALECysKIAALEQKIAALEQKGGYCONH2 AC-QIA
ALEQKIAALECysKIAALEQKIAALEQKGGYCONH2
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Structures Based on the Synthetic Peptide (C-14)
AC-QIAALEQKIAALECysKIAALEQKIAALEQKGGYCONH2 AC-QIA
ALEQKIAALECysKIAALEQKIAALEQKGGYCONH2
(Coiled-coil)
The sequence of the synthetic peptide (C-14) was
designed to provide

• A rigid linear (coiled-coil) structure
• Metal-binding cysteine (-SH) residues in middle
  of structure
• Self-assembly properties in
  Hydrophobic atmosphere

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In this project we applied metals and peptides to
create new and innovative structures.
Metal-peptides Monomer Structures
NEt42Re(CO)3Br3
2 HS Peptide
Au
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Self-Assembly Process by formation of
coiled-coils
Formation of a 180º metal-peptide complex (Gold)
Au 2C-14
Formation of a 90º metal-peptide complex (
Rhenium Platinum)
Pt 2C-14
Re2C-14

• To utilize directional bonding properties that
  would be conducive to our study we worked with
  linear (Au) and square planar (Re and Pt) metal
  complexes. Also the synthetic peptide (C-14) was
  sequenced to provide properties which would be
  favorable in our experimental conditions.

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Characterization of metal-peptide assemblies by
SDS-PAGE
Ideal Nanotube
SDS-PAGE
27 kDa 17 kDa 14 kDa 6 kDa
Trimers
Dimer
Monomer
Re2C-14
Au 2C-14
Standard
Pt 2C-14
Peptide C-14
Metal
Coiled-coil peptide
With this combination of metals and peptide, we
test for metal-peptide structures that may
contain two or more units of the metal-peptide
complex. The principle idea of this work is to
construct metal-peptide complexes for example,
dimers, trimers, and tube structures.
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Purification of metal-peptide complex
SDS-PAGE
27 kDa 17 kDa 14 kDa 6 kDa
SDS-PAGE results showing the presence of discrete
higher molecular weight metal-peptide assemblies
upon reacting C-14 with Platinum and Rhenium in
methanol.
Pt1 Pt2 Pt3 Re1 Re2 Re3 Re4 St
2
2
1
1
3
4
3
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Conclusion

• Results indicate that new peptide assemblies can
  be form through cross-linking (covalent capture)
  of the peptide of coiled-coil structure.
• Related work, which focus on the formation of
  metal-peptide complex, with determined geometry,
  shows that evidence for formation of
  metal-peptide nanoassemblies.
• Purification of the metal-peptide structures is
  possible.

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Future work

• Future work will include purification of a stable
  metal-peptide complexes and following
  characterization of possible metal-peptide
  assemblies.