Journal article
Investigating the Formation of a Repulsive Hydrogel of a Cationic 16mer Peptide at Low Ionic Strength in Water by Vibrational Spectroscopy and Rheology
The journal of physical chemistry. B, v 120(38), pp 10079-10090
29 Sep 2016
PMID: 27582028
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
The cationic peptide (AAKA)(4) (AK16) exhibits a high propensity for aggregation into beta-sheet-like structures in spite of the high positive charge of its protonated lysine side chains. Upon incubation into an aqueous solution, the peptide maintains a metastable beta-sheet-like structure with fibrillar content, the apparent stability of which increases with peptide concentration. In the presence of a sufficiently high concentration of anions, the peptide spontaneously forms a hydrogel at millimolar concentrations. Interestingly, we find that even in the absence of gel-supporting anions, the peptide is capable of forming a hydrogel in the centimolar range. Rheological data reveal that the gel is a stable elastic solid, These data show that the peptide can overcome the repulsive interactions between the positively charged ammonium groups of the lysine residues. The addition of 1 M NaCl just accelerates this process, Atomic force microscopy images of the peptide gel reveal fibrils with thicknesses between 4 and 8 nm, which suggests that they contain multiple layers of sheets. We propose that long tapes of beta-sheet are arranged in fibrils via stacking of alternating interfaces induced by hydrophobic interactions between alanine side chains and by the formation of a hydrogen bonded water network between hydrophilic sides of AK16 beta-sheets, which leads to the observed immobilization of the solvent in the formed hydrogel. Water immobilization is proposed as the likely cause for a significant increase in the amide I' oscillator strength of the formed beta-sheet structures.
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Details
- Title
- Investigating the Formation of a Repulsive Hydrogel of a Cationic 16mer Peptide at Low Ionic Strength in Water by Vibrational Spectroscopy and Rheology
- Creators
- David DiGuiseppi - Drexel Univ, Dept Chem, 3141 Chestnut St, Philadelphia, PA 19104 USAJodi Kraus - Drexel Univ, Dept Chem, 3141 Chestnut St, Philadelphia, PA 19104 USASiobhan E. Toal - University of PennsylvaniaNicolas Alvarez - Drexel UniversityReinhard Schweitzer-Stenner - Drexel University
- Publication Details
- The journal of physical chemistry. B, v 120(38), pp 10079-10090
- Publisher
- American Chemical Society; Washington, DC
- Number of pages
- 12
- Grant note
- Chemistry Department at Drexel University
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology; [Retired Faculty]; Chemical and Biological Engineering; Chemistry
- Web of Science ID
- WOS:000384626300005
- Scopus ID
- 2-s2.0-85064689650
- Other Identifier
- 991019167949904721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Chemistry, Physical