title: The effect of exposing a critical hydrophobic patch on amyloidogenicity and fibril structure of insulin.
abstract: It is widely accepted that the formation of amyloid fibrils is one of the natural properties of proteins. The amyloid formation process is associated with a variety of factors, among which the hydrophobic residues play a critical role. In this study, insulin was used as a model to investigate the effect of exposing a critical hydrophobic patch on amyloidogenicity and fibril structure of insulin. Porcine insulin was digested with trypsin to obtain desoctapeptide-(B23-B30) insulin (DOI), whose hydrophilic C-terminal of B-chain was removed and hydrophobic core was exposed. The results showed that DOI, of which the ordered structure (predominantly α-helix) was markedly decreased, was more prone to aggregate than intact insulin. As to the secondary structure of amyloid fibrils, DOI fibrils were similar to insulin fibrils formed under acidic condition, whereas under neutral condition, insulin formed less polymerized aggregates by showing decreased β-sheet contents in fibrils. Further investigation on membrane damage and hemolysis showed that DOI fibrils induced significantly less membrane damage and less hemolysis of erythrocytes compared with those of insulin fibrils. In conclusion, exposing the hydrophobic core of insulin can induce the increase of amyloidogenicity and formation of higher-order polymerized fibrils, which is less toxic to membranes.
authors.affiliation: Tongji School of Pharmacy, Huazhong University of Science & Technology, Wuhan, Hubei 430030, PR China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Lianqi
authors.initials: L
authors.lastname: Huang
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.forename: Yue
authors.initials: Y
authors.lastname: Sun
authors.forename: Hao
authors.initials: H
authors.lastname: Gong
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Ling
authors.initials: L
authors.lastname: Zheng
authors.forename: Kun
authors.initials: K
authors.lastname: Huang
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D000818:Animals; D004912:Erythrocytes / Q000473:pathology; D006461:Hemolysis; D057927:Hydrophobic and Hydrophilic Interactions; D007328:Insulin / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D013552:Swine
chemical_list: D000682:Amyloid; D007328:Insulin
keywords: 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphocholine; 2-oleoyl-1-palmitoyl-sn-glycerol-3-phospho-rac(1-glycerol) sodium salt; Amyloidogenicity; CD; DOI; Desoctapeptide-(B23–B30) insulin (DOI); Fibril structure; Hemolysis; Membrane damage; POPC; POPG; Porcine insulin; RP-HPLC; TEM; ThT; circular dichroism; desoctapeptide-(B23–B30) insulin; reversed phase high performance liquid chromatography; thioflavin-T; transmission electron-microscopy