Structures of self-assembled amphiphilic peptide-heterodimers: effects of concentration, pH, temperature and ionic strength

Handle URI:
http://hdl.handle.net/10754/599779
Title:
Structures of self-assembled amphiphilic peptide-heterodimers: effects of concentration, pH, temperature and ionic strength
Authors:
Luo, Zhongli; Åkerman, Björn; Zhang, Shuguang; Nordén, Bengt
Abstract:
The amphiphilic double-tail peptides AXG were studied regarding secondary structure and self-assembly in aqueous solution. The two tails A = Ala 6 and G = Gly6 are connected by a central pair X of hydrophilic residues, X being two aspartic acids in ADG, two lysines in AKG and two arginines in ARG. The peptide AD (Ala6Asp) served as a single-tail reference. The secondary structure of the four peptides was characterized by circular dichroism spectroscopy under a wide range of peptide concentrations (0.01-0.8 mM), temperatures (20-98 °C), pHs (4-9.5) and ionic strengths. In salt-free water both ADG and AD form a β-sheet type of structure at high concentration, low pH and low temperature, in a peptide-peptide driven assembly of individual peptides. The transition has a two-state character for ADG but not for AD, which indicates that the added tail in ADG makes the assembly more cooperative. By comparison the secondary structures of AKG and ARG are comparatively stable over the large range of conditions covered. According to dynamic light scattering the two-tail peptides form supra-molecular aggregates in water, but high-resolution AFM-imaging indicate that ordered (self-assembled) structures are only formed when salt (0.1 M NaCl) is added. Since the CD-studies indicate that the NaCl has only a minor effect on the peptide secondary structure we propose that the main role of the added salt is to screen the electrostatic repulsion between the peptide building blocks. According to the AFM images ADG and AKG support a correlation between nanofibers and a β-sheet or unordered secondary structure, whereas ARG forms fibers in spite of lacking β-sheet structure. Since the AKG and ARG double-tail peptides self-assemble into distinct nanostructures while their secondary structures are resistant to environment factors, these new peptides show potential as robust building blocks for nano-materials in various medical and nanobiotechnical applications. © 2010 The Royal Society of Chemistry.
Citation:
Luo Z, Åkerman B, Zhang S, Nordén B (2010) Structures of self-assembled amphiphilic peptide-heterodimers: effects of concentration, pH, temperature and ionic strength. Soft Matter 6: 2260. Available: http://dx.doi.org/10.1039/b926962b.
Publisher:
Royal Society of Chemistry (RSC)
Journal:
Soft Matter
Issue Date:
2010
DOI:
10.1039/b926962b
Type:
Article
ISSN:
1744-683X; 1744-6848
Sponsors:
BN acknowledges funding from the King Abdullah University of Science and Technology (KAUST). BA acknowledges a grant from the Swedish Research Council. Johan Bergenholtz is thanked for assistance in the DLS measurements. ZL thanks Per Lincoln, Niklas Bosaeus and Johanna Andersson for assistance and helpful discussions.
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Full metadata record

DC FieldValue Language
dc.contributor.authorLuo, Zhonglien
dc.contributor.authorÅkerman, Björnen
dc.contributor.authorZhang, Shuguangen
dc.contributor.authorNordén, Bengten
dc.date.accessioned2016-02-28T06:09:37Zen
dc.date.available2016-02-28T06:09:37Zen
dc.date.issued2010en
dc.identifier.citationLuo Z, Åkerman B, Zhang S, Nordén B (2010) Structures of self-assembled amphiphilic peptide-heterodimers: effects of concentration, pH, temperature and ionic strength. Soft Matter 6: 2260. Available: http://dx.doi.org/10.1039/b926962b.en
dc.identifier.issn1744-683Xen
dc.identifier.issn1744-6848en
dc.identifier.doi10.1039/b926962ben
dc.identifier.urihttp://hdl.handle.net/10754/599779en
dc.description.abstractThe amphiphilic double-tail peptides AXG were studied regarding secondary structure and self-assembly in aqueous solution. The two tails A = Ala 6 and G = Gly6 are connected by a central pair X of hydrophilic residues, X being two aspartic acids in ADG, two lysines in AKG and two arginines in ARG. The peptide AD (Ala6Asp) served as a single-tail reference. The secondary structure of the four peptides was characterized by circular dichroism spectroscopy under a wide range of peptide concentrations (0.01-0.8 mM), temperatures (20-98 °C), pHs (4-9.5) and ionic strengths. In salt-free water both ADG and AD form a β-sheet type of structure at high concentration, low pH and low temperature, in a peptide-peptide driven assembly of individual peptides. The transition has a two-state character for ADG but not for AD, which indicates that the added tail in ADG makes the assembly more cooperative. By comparison the secondary structures of AKG and ARG are comparatively stable over the large range of conditions covered. According to dynamic light scattering the two-tail peptides form supra-molecular aggregates in water, but high-resolution AFM-imaging indicate that ordered (self-assembled) structures are only formed when salt (0.1 M NaCl) is added. Since the CD-studies indicate that the NaCl has only a minor effect on the peptide secondary structure we propose that the main role of the added salt is to screen the electrostatic repulsion between the peptide building blocks. According to the AFM images ADG and AKG support a correlation between nanofibers and a β-sheet or unordered secondary structure, whereas ARG forms fibers in spite of lacking β-sheet structure. Since the AKG and ARG double-tail peptides self-assemble into distinct nanostructures while their secondary structures are resistant to environment factors, these new peptides show potential as robust building blocks for nano-materials in various medical and nanobiotechnical applications. © 2010 The Royal Society of Chemistry.en
dc.description.sponsorshipBN acknowledges funding from the King Abdullah University of Science and Technology (KAUST). BA acknowledges a grant from the Swedish Research Council. Johan Bergenholtz is thanked for assistance in the DLS measurements. ZL thanks Per Lincoln, Niklas Bosaeus and Johanna Andersson for assistance and helpful discussions.en
dc.publisherRoyal Society of Chemistry (RSC)en
dc.titleStructures of self-assembled amphiphilic peptide-heterodimers: effects of concentration, pH, temperature and ionic strengthen
dc.typeArticleen
dc.identifier.journalSoft Matteren
dc.contributor.institutionChalmers University of Technology, Göteborg, Swedenen
dc.contributor.institutionMassachusetts Institute of Technology, Cambridge, United Statesen
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