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

• Published in: Chemistry : a European journal Vol. 18; no. 39; pp. 12452 - 12457
• Main Authors: Mineo, Placido, Micali, Norberto, Villari, Valentina, Donato, Maria Grazia, Scamporrino, Emilio
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 24.09.2012; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Amino acids; Amino Acids - chemistry; Chemistry; Circular Dichroism; cobalt; Cobalt - chemistry; Dichroism; Fluorescence; Mathematical analysis; Metalloporphyrins - chemistry; molecular recognition; Molecular Structure; porphyrinoids; Porphyrins - chemistry; Protein folding; Proteins; Proteins - chemistry; Recognition; Residues; Spectrometry, Fluorescence; Spectroscopy
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201200784

The recognition of some globular proteins was carried out in aqueous solution, at micromolar concentrations, by 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 occurred on the protein surface. In particular, spectroscopic evidence showed the formation of supramolecular complexes without disruption of the native structure of the proteins and, furthermore, that signal changes were characteristic of each Co–P/protein system, so that they could be used as a highly sensitive analytical tool for protein recognition. The relative association constants were proportional to the protein molecular masses (and then to the number of amino acid residues). Who's who? A new uncharged cobalt–porphyrin (Co–P) was used as a molecular probe for protein sensing in aqueous solutions. Spectroscopic changes (UV/Vis, circular dichroism, and time‐resolved fluorescence) were characteristic of each Co–P/protein system and could be used as a highly sensitive analytical tool for protein studies (see figure).