Early Stages of De Novo Designed Beta-Hairpin Peptide Self-Assembly

ORAL

Abstract

In aqueous solution, MAX 1 peptide is unfolded and does not self-assemble. The peptide intramolecularly folds into a beta-hairpin when the electrostatic interactions between charged residues are screened through increasing the ionic strength at neutral pH. Beta-hairpin molecules supramolecularly assemble via hydrophobic collapse and hydrogen bonding into a 3-D hydrogel network. By combining the results of CD, cryo-TEM, DLS, and oscillatory rheology, we understand that the self-assembly proceeds by nucleation of monodisperse (3 nm wide) beta-sheet fibrils, which elongate, branch and cross-link to form clusters of fibrils. Assembly kinetics at this early stage indicates power law growth with assembly time. Eventually, clusters of fibrils interpenetrate to form a percolated network, as evidenced by the increasing network rigidity. The early stage assembly process will be discussed and compared to published gelation models.

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Authors

  • Tuna Yucel

    • Department of Materials Science and Engineering, Delaware Biotechnology Institute, University of Delaware, Newark, DE 19716

  • Joel P. Schneider

    • Chemistry and Biochemistry, University of Delaware
    • Department of Chemistry and Biochemistry
    • Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716

  • Darrin Pochan

    • Materials Science \& Engineering, University of Delaware
    • University of Delaware
    • Dept. of Materials Sci. and Eng., University of Delaware
    • Materials Science and Engineering
    • Department of Materials Science and Engineering and Delaware Biotechnology Institute, University of Delaware
    • Department of Materials Science and Engineering, Delaware Biotechnology Institute, University of Delaware, Newark, DE 19716