Changes in Secondary Structure of Human Prion Protein Peptide 30-90 under the Influence of Selected Dicationic and Anionic Surfactants

Abstract

The peptide (PrP30-90), which was used in this study, was designed on the basis of amino acid sequence of the unstructured N-terminal domain of human prion protein. Flexibility of this moiety and physicochemical properties of PrP N-terminal domain are related to the ability of prion protein to bind metal cations and are probably linked with the pathological conformational changes and formation insoluble deposits of this protein in the brain, which were observed in transmissible spongiform encephalopathies (e.g. Creutzfeldt-Jakob disease, CJD) [1]. This peptide, as well as N-terminal domain of PrP, possesses octarepeat sequences containing four histidine residues which overlap with binding sites of metal ions (copper, zinc etc). Interactions with surfactants probably could influence secondary structure of N-terminal domain or even full human prion protein. The present study was aimed at determination of the effects of cationic gemini imidazolium surfactant and anionic surfactant with different spacer groups on secondary structure of human prion protein at different pH values. The studies were carried out in MES buffer (pH 5.5) and phosphate buffer (pH 7,4) using circular dichroism (CD, Fourier transform infrared spectroscopy (FTIR) spectroscopy, NMR diffusometry and transmission electron microscopy (TEM). This work was supported by the funds from the National Science Centre (Poland) granted on the basis of decision no. 2016/23/N/ST5/02013. [1] Cobb N.J., Surewicz W.K. (2009) Biochemistry. 48(12), 2574-2585.