Antiparallel coiled coil crosslinks in self-assembled β-hairpin hydrogels

ORGN 435

Radhika P. Nagarkar, nagarkar@udel.edu and Joel P. Schneider, schneijp@udel.edu. Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716
A responsive self-assembling peptide consisting of an amphiphilic β-hairpin appended to a helix capable of forming homodimeric anti-parallel coiled coils, has been designed. This design enables multiple, distinct triggering mechanisms for hydrogelation and additional crosslinking. Folding of the each domain (helical and β-sheet) can be triggered by either pH or temperature. The β-hairpin domain was known to form physically crosslinked hydrogels with fibrillar nanostructure. Additional non-covalent crosslinks can be potentially formed between the β-hairpin fibrils by triggering the folding of the coiled coil domains. CD and FTIR spectroscopies probed the change in secondary conformation from α-helical to predominately β-sheet at high temperatures. Homodimer specificity of the coiled coils (appended to the unfolded β-hairpins) was confirmed using analytical ultracentrifugation. Such two-trigger materials can find potential application in systems that modulate stiffness by varying the nature and density of crosslinks in response to an external stimulus.