A Tetramer Derived from Islet Amyloid Polypeptide.
Wang, Y., Kreutzer, A.G., Truex, N.L., Nowick, J.S.(2017) J Org Chem 82: 7905-7912
- PubMed: 28661686 
- DOI: https://doi.org/10.1021/acs.joc.7b01116
- Primary Citation of Related Structures:  
5UHR - PubMed Abstract: 
Aggregation of the islet amyloid polypeptide (IAPP) to form fibrils and oligomers is important in the progression of type 2 diabetes. This article describes X-ray crystallographic and solution-state NMR studies of peptides derived from residues 11-17 of IAPP that assemble to form tetramers. Incorporation of residues 11-17 of IAPP (RLANFLV) into a macrocyclic β-sheet peptide results in a monomeric peptide that does not self-assemble to form oligomers. Mutation of Arg 11 to the uncharged isostere citrulline gives peptide homologues that assemble to form tetramers in both the crystal state and in aqueous solution. The tetramers consist of hydrogen-bonded dimers that sandwich together through hydrophobic interactions. The tetramers share several features with structures reported for IAPP fibrils and demonstrate the importance of hydrogen bonding and hydrophobic interactions in the oligomerization of IAPP-derived peptides.
Organizational Affiliation: 
Department of Chemistry, University of California, Irvine , Irvine, California 92697-2025, United States.