Metallo-Porphyrins as probes, storing system and logic gate, in supramolecular complexes with Z-DNA.

Porphyrins are quite versatile molecules successfully used in many fields: from nanotechnology to biomedicine. These hetero-aromatic macrocycles present remarkable electronic properties which bring to attractive spectroscopic features. The non-covalent interactions of water-soluble achiral porphyrins with chiral templates have been exploited to detect and/or amplify the matrix handedness. The interaction of achiral cationic porphyrins with DNA has been extensively studied and utilized as reporters of different sequences of DNA bases.[1-3] Nevertheless, few studies have been published on the capability of these macrocycles to discriminate among the various nucleic acids conformations.[4,5] Recently we have reported that a cationic Zn(II)porphyrin (ZnT4) and an anionic Ni(II)porphyrin (NiTPPS) were able to spectroscopically detect the left-handed Z-DNA under highly competitive conditions.[6] NiTPPS can interact with DNA if the electrostatic repulsion between the porphyrin and the double negative helix is properly shielded. This is accomplished through the action of the protonated form of spermine, which is also used to promote the conformational transition from B-form to Z-form. Moreover, thanks to its peculiar properties, NiTPPS/Spermine/Z-DNA complex shows to be quite a versatile system. In fact, as response to pH perturbations, it is able to reversibly release the chiral information stored in the porphyrin and/or in the DNA helix portion of the supramolecular complex.[7] Finally, using pH and temperature as input and porphyrin ICD as output, our system behaves as a reversible AND logic gate. 1. R. J. Fiel, J. C. Howard, E. H. Mark, N. DattaGupta, Nucl. Acid Res. 1979, 6: 3093-3118. 2. R. F. Pasternack, Chirality 2003, 15: 329-332. 3. S. Lee, S. H. Jeon, B.-J. Kim, S. W. Han, H. G. Jang, S. K. Kim, Biophys. Chem. 2001, 92: 35-45. 4. C. Bustamante, S. Gurrieri, R. F. Pasternack, R. Purrello, E. Rizzarelli, Biopolymers 1994, 34: 1099-1104. 5. R .F. Pasternack, S. Gurrieri, R. Lauceri, R. Purrello, Inorg. Chim. Acta 1996, 246: 7-12. 6. a) M. Balaz, M. De Napoli, A. E. Holmes, A. Mammana, K. Nakanishi, N. Berova, R. Purrello Angew. Chem. Int. Ed. 2005, 44: 4006-4009. b) A. D'Urso, J. K. Choi, M. Shabbir-Hussain, F. N. Ngwa, M. I. Lambousis, R. Purrello, M. Balaz, Biochem. Biophys. Res. Commun. 2010, 397, 329–332. c) A. D'Urso, A. E. Holmes, N. Berova, M. Balaz, R. Purrello, Chem. Asian J. 2011, 6, 3104–3109; d) A. E. Holmes, J. K. Choi, J. Francis, A. D’Urso, M. Balaz, J. Inorg. Biochem. 2012, 110, 18–20. 7. A. D'Urso, A. Mammana, M. Balaz, A. E. Holmes, N. Berova, R. Lauceri, R. Purrello, J. Am. Chem. Soc. 2009, 131, 2046–2047.