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Temperature and pH effects on biophysical and morphological properties of self‐assembling peptide RADA16‐I
Author(s) -
Ye Zhaoyang,
Zhang Hangyu,
Luo Hanlin,
Wang Shunkang,
Zhou Qinghan,
DU Xinpeng,
Tang Chengkang,
Chen Liyan,
Liu Jingping,
Shi YingKang,
Zhang ErYong,
EllisBehnke Rutledge,
Zhao Xiaojun
Publication year - 2008
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/psc.988
Subject(s) - peptide , chemistry , biophysics , self assembly , hydrogen bond , globular protein , ionic bonding , self assembling peptide , crystallography , protonation , ion , biochemistry , organic chemistry , molecule , biology
It has been found that the self‐assembling peptide RADA 16‐I forms a β‐sheet structure and self‐assembles into nanofibers and scaffolds in favor of cell growth, hemostasis and tissue‐injury repair. But its biophysical and morphological properties, especially for its β‐sheet and self‐assembling properties in heat‐ and pH‐denatured conditions, remain largely unclear. In order to better understand and design nanobiomaterials, we studied the self‐assembly behaviors of RADA16‐I using CD and atomic force microscopy (AFM) measurements in various pH and heat‐denatured conditions. Here, we report that the peptide, when exposed to pH 1.0 and 4.0, was still able to assume a typical β‐sheet structure and self‐assemble into long nanofiber, although its β‐sheet content was dramatically decreased by 10% in a pH 1.0 solution. However, the peptide, when exposed to pH 13.0, drastically lost its β‐sheet structure and assembled into different small‐sized globular aggregates. Similarly, the peptide, when heat‐denatured from 25 to 70 °C, was still able to assume a typical β‐sheet structure with 46% content, but self‐assembled into small‐sized globular aggregates at much higher temperature. Titration experiments showed that the peptide RADA16‐I exists in three types of ionic species: acidic (fully protonated peptide), zwitterionic (electrically neutral peptide carrying partial positive and negative charges) and basic (fully deprotonated peptide) species, called ‘super ions’. The unordered structure and β‐turn of these ‘super ions’ via hydrogen or ionic bonds, and heat Brownian motion under the above denatured conditions would directly affect the stability of the β‐sheet and nanofibers. These results help us in the design of future nanobiomaterials, such as biosensors, based on β‐sheets and environmental changes. These results also help understand the pathogenesis of the β‐sheet‐mediated neuronal diseases such as Alzheimer's disease and the mechanism of hemostasis. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.