Xiao-Bo Mao,
Chen-Xuan Wang,
Xing-Kui Wu,
Xiao-Jing Ma,
Lei Liu,
Lan Zhang,
Lin Niu,
Yuan-Yuan Guo,
Deng-Hua Li,
Yan-Lian Yang, and
Chen Wang
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 IAPP8–37 (hIAPP8–37) assembly were observed featuring a hairpin structure. The multiplicity in rIAPP assembly structures indicates the polydispersity of the rat IAPP8–37 (rIAPP8–37) beta-like motifs. The bimodal length distribution of beta structure motifs for rIAPP8–37 R18H indicates the multiple beta segments linked by turns. The IAPP8–37 analogs share common structure motifs of IAPP8–17 and IAPP26–37 with the most probable key sites at positions around Ser19/Ser20 and Gly24. 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.
Journal: Proceedings of the National Academy of Sciences
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