His18 promotes reactive oxidative stress production in copper-ion mediated human islet amyloid polypeptide aggregation

Gengyang Huo; Wenyong Chen; Jianhua Wang; Xinxing Chu; Wei Xu; Bin Li; Yi Zhang; Binqian Xu; Xingfei Zhou

doi:10.1039/c9ra09943c

His18 promotes reactive oxidative stress production in copper-ion mediated human islet amyloid polypeptide aggregation

RSC Adv. 2020 Feb 4;10(10):5566-5571. doi: 10.1039/c9ra09943c.

Authors

Gengyang Huo¹, Wenyong Chen¹, Jianhua Wang¹, Xinxing Chu^{1

2}, Wei Xu¹, Bin Li², Yi Zhang², Binqian Xu³, Xingfei Zhou¹

Affiliations

¹ School of Physics Science and Technology, Ningbo University China zhouxingfei@nbu.edu.cn.
² Shanghai Advanced Research Institute, Chinese Academy of Sciences China.
³ Single Molecule Study Laboratory, College of Engineering, University of Georgia Athens Georgia 30602 USA.

Abstract

Copper ions play a critical role in human islet amyloid polypeptide (hIAPP) aggregation, which has been found in more than 90% of patients with type-2 diabetes (T2D). The role of Cu(ii) in the cell cytotoxicity with hIAPP has been explored in two aspects: inhibiting the formation of fibrillar structures and stimulating the generation of reactive oxygen species (ROS). In this work, we carried out spectroscopic studies of Cu(ii) interacting with several hIAPP fragments and their variants as well. Electron paramagnetic resonance (EPR) measurements and Amplex Red analysis showed that the amount of H₂O₂ generated in hIAPP(11-28) solution co-incubated with Cu(ii) was remarkably more than hIAPP(1-11) and hIAPP(28-37). Furthermore, the H₂O₂ level was seriously reduced when His18 of hIAPP(11-28) was replaced by Arg(R) or Ser(S), indicating that His18 is the key residue of Cu(ii) binding to hIAPP(11-28) to promote H₂O₂ generation. This is likely because the donation of electrons from the peptide to Cu(ii) ions would result in the formation of the redox-active complexes, which could stimulate the formation of H₂O₂. Overall, this study provides further insight into the molecular mechanism of Cu(ii) induced ROS generation.