title: Beta structure motifs of islet amyloid polypeptides identified through surface-mediated assemblies.
abstract: We report here the identification of the key sites for the beta structure motifs of the islet amyloid polypeptide (IAPP) analogs by using scanning tunneling microscopy (STM). Duplex folding structures in human IAPP(8-37) (hIAPP(8-37)) assembly were observed featuring a hairpin structure. The multiplicity in rIAPP assembly structures indicates the polydispersity of the rat IAPP(8-37) (rIAPP(8-37)) beta-like motifs. The bimodal length distribution of beta structure motifs for rIAPP(8-37) R18H indicates the multiple beta segments linked by turns. The IAPP(8-37) analogs share common structure motifs of IAPP(8-17) and IAPP(26-37) with the most probable key sites at positions around Ser(19)/Ser(20) and Gly(24). These observations reveal the similar amyloid formation tendency in the C and N terminus segments because of the sequence similarity, while the differences in specific amino acids at each key site manifest the effect of sequence variations. The results could be beneficial for studying structural polymorphism of amyloidal peptides with multiple beta structure motifs.
authors: National Center for Nanoscience and Technology, Beijing 100190, China.
authors: Xiao-Bo
authors: XB
authors: Mao
authors: Chen-Xuan
authors: CX
authors: Wang
authors: Xing-Kui
authors: XK
authors: Wu
authors: Xiao-Jing
authors: XJ
authors: Ma
authors: Lei
authors: L
authors: Liu
authors: Lan
authors: L
authors: Zhang
authors: Lin
authors: L
authors: Niu
authors: Yuan-Yuan
authors: YY
authors: Guo
authors: Deng-Hua
authors: DH
authors: Li
authors: Yan-Lian
authors: YL
authors: Yang
authors: Chen
authors: C
authors: Wang
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D006801:Humans; D058228:Islet Amyloid Polypeptide / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016252:Microscopy, Scanning Tunneling; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D051381:Rats
chemical_list: D058228:Islet Amyloid Polypeptide; D010446:Peptide Fragments