pH-sensitivity and Conformation Change of the N-terminal Methacrylated Peptide VK20
- PDF / 1,076,800 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 0 Downloads / 146 Views
pH-sensitivity and Conformation Change of the N-terminal Methacrylated Peptide VK20 Zewang You1,2, Marc Behl1, Candy Löwenberg1, and Andreas Lendlein1,2 Institute of Biomaterial Science, Helmholtz-Zentrum Geesthacht, Kantstr. 55, 14513 Teltow, Germany 2 Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany 1
ABSTRACT N-terminal methacrylation of peptide MAX1, which is capable of conformational changes by variation of the pH, results in a peptide, named VK20. Increasing the reactivity of this terminal group enables further coupling reactions or chemical modifications of the peptide. However, this end group functionalization may influence the ability of conformational changes of VK20, as well as its properties. In this paper, the influence of pH on the transition between random coil and ß-sheet conformation of VK20, including the transition kinetics, were investigated. At pH values of 9 and higher, the kinetics of ß-sheet formation increased for VK20, compared to MAX1. The self-assembly into ß-sheets recognized by the formation of a physically crosslinked gel was furthermore indicated by a significant increase of G’. An increase in pH (from 9 to 9.5) led to a faster gelation of the peptide VK20. Simultaneously, G’ was increased from 460 ± 70 Pa (at pH 9) to 1520 ± 180 Pa (at pH 9.5). At the nanoscale, the gel showed a highly interconnected fibrillary network structure with uniform fibril widths of approximately 3.4 ± 0.5 nm (N=30). The recovery of the peptide conformation back to random coil resulted in the dissolution of the gel, whereby the kinetics of the recovery depended on the pH. Conclusively, the ability of MAX1 to undergo conformational changes was not affected by Nterminal methacrylation whereas the kinetics of pH-sensitive ß-sheet formations has been increased. INTRODUCTION In nature, specific functions are influenced just by small structural changes in the protein conformation. Inspired by this, peptides have been extensively exploited as building blocks for stimuli-responsive materials [1] with focus on the basic conformational motifs, such as α-helix, ß-sheet or coiled coil as structural elements. These conformational transitions were dynamic in response to the conditions of the environment, e.g. change of pH, salt, and temperature or presence of enzymes [2]. The integration of the peptide moieties into other materials enabled the control of their molecular organization e.g. assembly and disassembly of peptide-polymer conjugates [3] or peptide coated gold nanoparticles [4]. In some cases, the responsiveness on the molecular level resulted in macroscopic changes of the material properties, e.g. sol-gel transitions or volume changes in hydrogels. Regarding the integration of peptide moieties into other materials, the ability for hydrogen bonding and the flexibility of the peptides have to be maintained to allow the peptide to undergo conformational changes [5, 6]. Due to their easier synthetic accessibility compared to the relatively long α-helix/coiled coil pep
Data Loading...
