Metal ion exchange is receiving increasing attention as it is an essential process in biological systems. The Crans group has been investigating the transfer of Cu<sup>2+</sup> between various peptide complexes as a model for peptide transfer in amyloid beta, using static fluorescence quenching of tryptophan. In the following study I have been working on the transfer of Cu<sup>2+</sup> between a series of tri and tetra peptides. The rate will be determined using fluorescence spectroscopy and the method of initial rates. In this study we are examining Cu-complexes that contain a free unbound side chain and the effects of different amino acid groups. The transfer of copper(II) is measured using static fluorescence quenching of tryptophan (W) by having this complex react with an equivalent peptide with the unbound amino acid substituted with a W residue. At such low concentrations the fluorescence intensity is linearly proportional to concentration and as the tryptophan peptide’s fluorescence recovery is monitored over time a rate of exchange can be measured. These studies allow for measurement of the rate constants of interpeptidic Cu(II) transfer between homo tri and tetra peptides. Precision is extremely important in these experiments as the main purpose aside from simply obtaining the data is reproducibility. These data allow us to compare with the rate constants available in the literature for both tri and tetra peptides. We find that the tri-peptides often more readily transfer the Cu(II), but that the specific location of the His amino acid is important for the size of the rate constant.

Kinetic studies of interpeptidic Cu(II) exchange from Cu(II) tri- and tetrapeptide complexes

2019 Spring National Meeting

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