Reading of Protein Surfaces in the Native State at Micromolar Concentrations by a Chirogenetic Porphyrin Probe

The recognition of some globular proteins was carried out in aqueous solution, at micro molar concentration, using an uncharged symmetrical Cobalt-porphyrin (Co-P). By means of UV-vis, induced circular dichroism and fluorescence spectroscopy techniques, it was ascertained that the interactions between specific amino acid residues and Co-P occur on the protein surface. In particular, spectroscopic evidences showed the formation of supramolecular complexes without disruption of the native structure of the proteins and, furthermore, that the signal changes were characteristic of each Co-P/protein system so that they could be used as a highly sensitive analytical tool for the protein recognition. The relative association constants were proportional to the Protein Molecular Masses (and then to the aminoacids residues number).