Tau protein is a neuronal target which stabilizes microtubule structure [1]. High levels of metal ions in the brain may promote metallation of tau and trigger reactive oxygen species production and subsequent oxidative stress. Metal ion coordination to tau proteins and their peptide fragments has been previously reported [2]. However, very little is known about the catalytic ability of metallo-tau to generate hydrogen peroxide or participate in oxidation-reduction reactions with other biological molecules, such as ascorbic acid. In addition, the interactions between iron-rich proteins, ferritin, heme and transferrin, and tau have not been identified. Herein, we report on the solution electrochemical detection (CV, SWV, DPV) of Cu(II) coordination to tau protein and its R1-R4 peptide fragments. The coordination of R2 and R3 peptides to Cu(II) significantly reduced the current associated with Cu(II)/Cu(I) redox couple. The ability of Cu(II)-tau peptide to produce hydrogen peroxide was measured by fluorescence assay. For detection of ferritin, transferrin and heme binding to tau441 protein, the electrochemical impedance spectroscopy was used. The charge transfer resistance increased after transferrin binding but not ferritin binding. The binding was also evaluated as a function of iron-rich protein concentration and solution pH. The catalytic abilities of these metallo-tau films were tested in the presence of ascorbic acid.<br/><br/><br/>[1] Wingarten, M. D., Lockwood, A. H., Hwo, S. Y., Kirschner, M. W. Proc. Natl. Acad. Sci. U. S. A. 1975, 72, 1858-1862.<br/>[2] Zhou, L. X., Du, J. T., Zneg, Z. Y., Wu, W. H., Zhao, Y. F., Kanazawa, K., Ishizuka, Y., Nemoto, T., Nakanishi, H., Li, Y. M. Peptides, 2007, 28, 2229-2234; b) Ma, Q.F., Li, Y. M., Du, J. T., Kanazawa, K., Nemoto, T., Nakanishi, H., Zhao, Y. F. Biopolymers, 2005, 79, 74-85.

Electrochemical detection of metal coordination to tau peptides/protein and evaluation of hydrogen peroxide formation

251st National Meeting (2016)

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