Learning from prion-derived peptides for designing novel phosphorylation-sensitive peptide probes.

Novel catalytic peptides highly active in conversion of hydrogen peroxide to superoxide are newly designed and proposed as novel probes for assessing the cellular protein phosphorylation/dephosphorylation events possibly available for future clinical applications. One of model peptide was invented by fusing the copper-binding catalytic peptide and Erk1/2 MAP kinase kinase substrate peptide. In order to demonstrate that this type of probes is phosphorylation-sensitive, preliminary data was obtained with non-phosphorylated and phosphorylated peptides at two phosphorylation sites, namely, threonine and tyrosine residues. As expected, model phosphorylations effectively lowered the catalytic activity of the peptide. This is the first implication that phosphorylation-controllable enzyme mimics could be artificially invented. In addition, the author propose a possible application of this type of peptides as the tools or components for constructing a simplified in vitro signaling system processing the phosphorylation signals into the oxidative signals possibly affecting the fate of the living cells.