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Title: Self-Assembly and Molecular Dynamics of Peptide-Functionalized Polyphenylene Dendrimers

Abstract

The self-assembly mechanism and the associated molecular dynamics are studied for a series of poly-L-lysine-functionalized polyphenylene dendrimer melts as a function of the core size (generation), functionality, and polypeptide length using X-rays, solid-state NMR, calorimetry, and dielectric spectroscopy. A striking dependence of the polyphenylene self-assembly on the poly-L-lysine length is shown. In addition, the type ({alpha}helix/{beta}-sheet) of peptide secondary structure is controlled by the packing restrictions imposed by the polyphenylene core. We show that constrained poly-L-lysines can adopt different secondary structures from their linear analogues. The dynamic investigation revealed significant mobility associated solely with the polypeptide through three processes: a glass transition, a slower process associated with the relaxation of {alpha}-helical segments, and a glassy mode whose origin could be resolved by site-specific solid-state NMR techniques. Solid-state NMR studies further indicated a mobility gradient in going from the rigid peptide backbone to the side chains.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930237
Report Number(s):
BNL-80919-2008-JA
TRN: US200822%%1414
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Macromolecules; Journal Volume: 39
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CALORIMETRY; DIELECTRIC MATERIALS; DYNAMICS; FUNCTIONS; GLASS; LENGTH; MOBILITY; NUCLEAR MAGNETIC RESONANCE; ORIGIN; PEPTIDES; POLYPEPTIDES; RELAXATION; SIZE; SPECTROSCOPY; STOWING; national synchrotron light source

Citation Formats

Mondeshki,M., Milhov, G., Graf, R., Spiess, H., Mullen, K., Papadopoulos, P., Gitsas, A., and Floudas, G.. Self-Assembly and Molecular Dynamics of Peptide-Functionalized Polyphenylene Dendrimers. United States: N. p., 2006. Web. doi:10.1021/ma0621270.
Mondeshki,M., Milhov, G., Graf, R., Spiess, H., Mullen, K., Papadopoulos, P., Gitsas, A., & Floudas, G.. Self-Assembly and Molecular Dynamics of Peptide-Functionalized Polyphenylene Dendrimers. United States. doi:10.1021/ma0621270.
Mondeshki,M., Milhov, G., Graf, R., Spiess, H., Mullen, K., Papadopoulos, P., Gitsas, A., and Floudas, G.. Sun . "Self-Assembly and Molecular Dynamics of Peptide-Functionalized Polyphenylene Dendrimers". United States. doi:10.1021/ma0621270.
@article{osti_930237,
title = {Self-Assembly and Molecular Dynamics of Peptide-Functionalized Polyphenylene Dendrimers},
author = {Mondeshki,M. and Milhov, G. and Graf, R. and Spiess, H. and Mullen, K. and Papadopoulos, P. and Gitsas, A. and Floudas, G.},
abstractNote = {The self-assembly mechanism and the associated molecular dynamics are studied for a series of poly-L-lysine-functionalized polyphenylene dendrimer melts as a function of the core size (generation), functionality, and polypeptide length using X-rays, solid-state NMR, calorimetry, and dielectric spectroscopy. A striking dependence of the polyphenylene self-assembly on the poly-L-lysine length is shown. In addition, the type ({alpha}helix/{beta}-sheet) of peptide secondary structure is controlled by the packing restrictions imposed by the polyphenylene core. We show that constrained poly-L-lysines can adopt different secondary structures from their linear analogues. The dynamic investigation revealed significant mobility associated solely with the polypeptide through three processes: a glass transition, a slower process associated with the relaxation of {alpha}-helical segments, and a glassy mode whose origin could be resolved by site-specific solid-state NMR techniques. Solid-state NMR studies further indicated a mobility gradient in going from the rigid peptide backbone to the side chains.},
doi = {10.1021/ma0621270},
journal = {Macromolecules},
number = ,
volume = 39,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Relaxation of a self-assembled structure of 144 peptide amphiphile (PA) molecules into cylindrical nanofibers is studied using atomistic molecular dynamics simulations including explicit water with physiological ion concentration. The PA for these studies includes a hydrophobic alkyl chain that is attached to the N-terminus of the sequence SLSLAAAEIKVAV. The self-assembly is initiated with PA molecules in a roughly cylindrical configuration, as suggested from previous experimental and theoretical investigations, and the cylindrical configuration that results is found to be stable during 40 ns simulations. In the converged structure of the resulting nanofiber, the cylinder radius is ~44 Å, a result thatmore » is consistent with experimental results. Water and sodium ions can penetrate into the peptide portion of the fiber but not between the alkyl chains. Even though each PA has an identical sequence, a broad distribution of secondary structure is found in the converged structure of the nanofiber. The β-sheet population for the SLSL and IKV segments of the peptide is ~25%, which is consistent with previous circular dichroism results. We also found that the epitope sequence IKVAV is located on the surface of the nanofiber, as designed for the promotion of the neurite growth. Our findings will be useful for designing new PA fibers that have improved bioactive properties.« less
  • Relaxation of a self-assembled structure of 144 peptide amphiphile (PA) molecules into cylindrical nanofibers is studied using atomistic molecular dynamics simulations including explicit water with physiological ion concentration. The PA for these studies includes a hydrophobic alkyl chain that is attached to the N-terminus of the sequence SLSLAAAEIKVAV. The self-assembly is initiated with PA molecules in a roughly cylindrical configuration, as suggested from previous experimental and theoretical investigations, and the cylindrical configuration that results is found to be stable during 40 ns simulations. In the converged structure of the resulting nanofiber, the cylinder radius is ~44 Å, a result thatmore » is consistent with experimental results. Water and sodium ions can penetrate into the peptide portion of the fiber but not between the alkyl chains. Even though each PA has an identical sequence, a broad distribution of secondary structure is found in the converged structure of the nanofiber. The β-sheet population for the SLSL and IKV segments of the peptide is ~25%, which is consistent with previous circular dichroism results. We also found that the epitope sequence IKVAV is located on the surface of the nanofiber, as designed for the promotion of the neurite growth. Our findings will be useful for designing new PA fibers that have improved bioactive properties.« less