title: Identification of minimal peptide sequences in the (8-20) domain of human islet amyloid polypeptide involved in fibrillogenesis.
abstract: We have examined a series of overlapping peptide fragments from the 8-20 region of human islet amyloid polypeptide (IAPP) with the objective of defining the smallest fibril-forming domain. Peptide fragments corresponding to LANFLV (residues 12-17) and FLVHSS (residues 15-20) were strong enhancers of beta-sheet transition and fibril formation. Negative stain electron microscopy illustrated the ability of these peptide fragments to form fibrils independently when incubated alone in solution. Circular dichroism analysis revealed that when full-length human IAPP was incubated in the presence of these two fragments, fibrillogenesis was accelerated. While the two fragments, LANFLV and FLVHSS, were able to enhance the recruitment of additional IAPP molecules during fibril formation, the "seeding" activity of these peptides had no effect on altering IAPP-induced cytotoxcity as determined by cell culture studies. Therefore, this study has identified two internal IAPP peptide fragments within the 8-20 domain that may have a role in enhancing the folding and aggregation of human IAPP. These fragments are the smallest sequences identified, within the 8-20 region of hIAPP, that can independently form fibrils, and that can interact with IAPP to assemble into fibrils with characteristics similar as those formed by human IAPP alone.
authors.affiliation: Centre for Research in Neurodegenerative Diseases, University of Toronto, Tanz Neuroscience Building, 6 Queen's Park Crescent West, Ont., M5S 3H2, Toronto, Canada. l.scrocchi@utoronto.ca
authors.forename: Louise A
authors.initials: LA
authors.lastname: Scrocchi
authors.forename: Kathy
authors.initials: K
authors.lastname: Ha
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Ling
authors.initials: L
authors.lastname: Wu
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Paul E
authors.initials: PE
authors.lastname: Fraser
mesh_terms: D000682:Amyloid / Q000737:chemistry*; D000686:Amyloidosis / Q000378:metabolism*; D002478:Cells, Cultured; D002942:Circular Dichroism; D006801:Humans; D058228:Islet Amyloid Polypeptide; D008854:Microscopy, Electron; D010452:Peptide Biosynthesis; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013997:Time Factors
chemical_list: D000682:Amyloid; D058228:Islet Amyloid Polypeptide; D010455:Peptides