Ion-Mediated Adsorption of Amyloid-β Peptides at the Liquid/Liquid Interface: Insights from Electrochemistry and Molecular Dynamics Simulations

As a nice New Year’s gift, our article about Amyloid-β adsorbed at the ITIES was published in ACS Electrochemistry.¹ In this paper, we investigate the behaviour of two different peptides, Aβ(1-16) and Aβ(4-16), at the liquid|liquid interface.

There are many publication describing the adsorption of proteins at the ITIES (e.g. this one from our group²), but the details of the interaction are usually quite vague. One reason, of course, is that proteins are very large and contain many different functional domains. This makes it difficult to pinpoint specific interactions. In an attempt to understand these processes in more detail, we decided to focus our attention on shorter amino acid chains – here, peptides with up to 16 amino acid residues. These peptides are small enough that they can be studied computationally on an atomistic level within a reasonable timescale. The particular peptides choses are well-known from studies of Alzheimer’s disease, but they also form well-characterised complexes with Cu(II) ions, giving us another dimension to study.

Combining electrochemical and computational data showed that the ions present in the organic phase (here, DCE) play an important role when the Aβ adsorb on the ITIES. Thanks to molecular dynamic simulations, we could pinpoint which amino acid residues interact positively or negatively with the anions in the organic phase. We could also see a clear difference in the interaction when Cu(II) was added to the aqueous solution.

There are of course still many questions left to answer, but we hope that the study of smaller biomolecules at the ITIES can help us understand the the intricacies of the behaviour of larger molecules such as proteins and enzymes.

This work was done in collaboration with Shayon Bhattacharya from the University of Limerick, Ireland, who did all the molecular dynamics calculations. The experimental work was mainly performed by Geli, and this is Magda‘s first publication with her new post-wedding surname.

1. A. Holzinger, S. Bhattacharya, M. Z. Wiloch-Szyborska, M. Jönsson-Niedziółka
   Ion-Mediated Adsorption of Amyloid-β Peptides at the Liquid/Liquid Interface: Insights from Electrochemistry and Molecular Dynamics Simulations, ACS Electrochem (accepted). (link – OA)
2. M. Podrażka, E. Witkowska Nery, T. G. Henares, M. Jönsson-Niedziółka, and D. W. M. Arrigan
   Ion Transfer Voltammetry with an Electrochemical Pen, Anal. Chem. 92, 15997–16004. (link – OA)(blog)