Uncharged Water-Soluble Co(II)-Porphyrin: A Receptor for Aromatic alpha-Amino Acids (Articolo in rivista)

Type
Label
  • Uncharged Water-Soluble Co(II)-Porphyrin: A Receptor for Aromatic alpha-Amino Acids (Articolo in rivista) (literal)
Anno
  • 2005-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1021/jp052408u (literal)
Alternative label
  • Nicola Angelini; Norberto Micali; Placido Mineo; Emilio Scamporrino; Valentina Villari; Daniele Vitalini (2005)
    Uncharged Water-Soluble Co(II)-Porphyrin: A Receptor for Aromatic alpha-Amino Acids
    in The journal of physical chemistry. B
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Nicola Angelini; Norberto Micali; Placido Mineo; Emilio Scamporrino; Valentina Villari; Daniele Vitalini (literal)
Pagina inizio
  • 18645 (literal)
Pagina fine
  • 18651 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 109 (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo
  • 39 (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • CNR-Istituto per i Processi Chimico-Fisici, sez. Messina, Via La Farina 237, I-98123 Messina, Italy CNR-Istituto di Chimica e Tecnologia dei Polimeri, Viale Andrea Doria 6, I-95125 Catania, Italy Dipartimento di Scienze Chimiche, UniVersita' di Catania, Viale A. Doria 6, I-95125 Catania, Italy (literal)
Titolo
  • Uncharged Water-Soluble Co(II)-Porphyrin: A Receptor for Aromatic alpha-Amino Acids (literal)
Abstract
  • Changes in the UV-vis spectra and induced circular dichroism (ICD) signals observed, in correspondence with the porphyrin Soret region, for aqueous solutions of achiral 5,10,15,20-tetrakis{p-[ù-methoxy poly(oxyethylene)] phenyl}porphyrin cobalt (II) (Co-P) and aromatic alpha-L-amino acids (Trp and Phe) give direct evidence for the coordination between the Co-P and amino acids. Considering that Co-P, besides the Co atom (onefixation- point system), does not contain in the molecule active ligand groups and that no ICD signals have been observed in the case of Co-P/Ala, it has been concluded that hydrophobic interactions or stacking interactions between the aromatic rings of the porphyrin and those of Trp or Phe, acting as further amino acid (AA) fixation points, can strongly reduce the mobility of the chiral guest, thus permitting the generation of ICD signals. The effects of changes of both pH (in the range 2-9) and amino acid structure on the ICD phenomenon have also been investigated. In particular, the following have been observed: (i) strong ICD signals for all of the Co-P/N-acetyl amino acid aqueous solutions at pH 7, (ii) an unexpected ICD band with a bisignate form for the Co-P/Ala solution at pH 9 after long aging, and (iii) an opposite ICD signal when alpha-D-Phe and alpha-D-Trp enantiomers have been used. The data reported in this paper show how the binding mechanism between receptor and AAs changes by modulating properly the pH or the molecular structures and indicate that in these aqueous solutions the coordination Co-N is not the fundamental mechanism giving rise to the formation of the complexes and that the binding can be driven by hydrophobic interactions. These occurrences, through the analysis of the spectroscopic response (and, in particular, the form of the ICD band), can allow the recognition of AAs. (literal)
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