Physics Dept Seminar

November 6, Monday

Pleated and Rippled beta-Sheet Motifs in Supramolecular Peptide Materials

Prof. Bradley L. Nilsson

Univ. of Rochester, NY

(Bio/Materials Physics, Host: Dias)

Time: 11:45 am - 12:45 pm with 11:30 am teatime

Room: ECE 202

Peptide self-assembly into cross-beta fibrils composed of pleated beta-sheet structures is of fundamental importance in amyloid misfolding disorders and in the design of next-generation biomaterials. Recently, the Pauling rippled beta-sheet motif has emerged as the foundation of a novel class of supramolecular peptide biomaterial. The rippled beta-sheet motif as proposed by Pauling and Corey is composed of coassembled enantiomeric peptides arranged in an alternating L/D pattern within the beta-sheet structure. This alternating L/D orientation of enantiomers within the rippled beta-sheet gives a unique peptide cross-strand packing structure relative to the more common pleated beta-sheet motif. In the last decade, evidence for the formation of rippled beta-sheet structures from several peptide systems has emerged. However, some peptide systems have also been reported that exhibit a preference for self-sorting of enantiomers in racemic mixtures into all-L and all-D pleated beta-sheets. Thus, significant questions regarding the scope of rippled beta-sheet assembly remain. Herein, studies that explore the limits of coassembly of peptides of opposite chirality into rippled beta-sheets are presented. Specifically, the scope of rippled beta-sheet formation in three related peptide systems will be discussed. These systems include 1) the coassembly of L- and D-peptide enantiomers, 2) the coassembly of L- and D-peptides of similar sequence pattern but differing hydrophobic amino acids (quasi-enantiomers), and 3) the coassembly of L- and D-peptides that have identical amino acid content but with differing sequence patterns (constitutional isomers). These studies give insight into the scope of rippled and pleated beta-sheet formation in mixtures of peptides of opposite chirality.