title: Preparation of synthetic human islet amyloid polypeptide (IAPP) in a stable conformation to enable study of conversion to amyloid-like fibrils.
abstract: Human synthetic islet amyloid polypeptide (hIAPP) is rapidly converted to beta-sheet conformation and fibrils in aqueous media. Optimal solubility conditions for hIAPP were determined by circular dichroism spectroscopy and transmission electron microscopy. hIAPP in trifluoroethanol or hexafluoro-2-isopropanol (HFIP) diluted in water or phosphate buffer (PB) exhibited random structure which was converted to beta-sheet and fibrils with time. hIAPP, solubilised in HFIP, filtered and lyophilised remained in stable random structure for up to 7 days in water; in PB, insoluble aggregates precipitated from which protofilaments and fibrils formed with time. This suggests that amorphous aggregates of hIAPP could initiate islet amyloidosis in vivo.
authors.affiliation: Laboratory of Cellular Endocrinology, Department of Human Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, UK.
authors.forename: C E
authors.initials: CE
authors.lastname: Higham
authors.forename: E T
authors.initials: ET
authors.lastname: Jaikaran
authors.forename: P E
authors.initials: PE
authors.lastname: Fraser
authors.forename: M
authors.initials: M
authors.lastname: Gross
authors.forename: A
authors.initials: A
authors.lastname: Clark
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000138:chemical synthesis* / Q000648:ultrastructure; D000818:Animals; D052160:Benzothiazoles; D002942:Circular Dichroism; D006801:Humans; D058228:Islet Amyloid Polypeptide; D008969:Molecular Sequence Data; D020005:Propanols / Q000737:chemistry; D017433:Protein Structure, Secondary; D051381:Rats; D012995:Solubility; D013057:Spectrum Analysis; D013844:Thiazoles; D014270:Trifluoroethanol / Q000737:chemistry; D006845:Hydrocarbons, Fluorinated
chemical_list: D000682:Amyloid; D052160:Benzothiazoles; D058228:Islet Amyloid Polypeptide; D020005:Propanols; D013844:Thiazoles; D014270:Trifluoroethanol; C009462:thioflavin T; C001337:hexafluoroisopropanol; D006845:Hydrocarbons, Fluorinated