title: Turn and helical peptide spacers: combined distance and angular dependencies in the exciton-coupled circular dichroism of intramolecularly interacting bis-porphyrins.
abstract: In a previous study we examined by the exciton-coupled circular dichroic method the distance effect generated by three-rigid-turn and helical-peptide spacers. In this connection porphyrins were confirmed to be excellent reporter chromophores. In the present investigation we have completed this research by expanding the original analysis to the assessment of the combined role of the chromophore distance and orientation with use of the same porphyrin derivatives and additional four analogous spacers of different main-chain lengths. We find that not only the intramolecular separation of the chromophores, but the angular dependence between the directions of their effective transition moments as well, are responsible for the onset and modulation of the intensity of the exciton-coupling phenomenon of the porphyrin Soret band.
authors.affiliation: Institute of Biomolecular Chemistry, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy.
authors.forename: Ivan
authors.initials: I
authors.lastname: Guryanov
authors.forename: Alessandro
authors.initials: A
authors.lastname: Moretto
authors.forename: Sandro
authors.initials: S
authors.lastname: Campestrini
authors.forename: Quirinus B
authors.initials: QB
authors.lastname: Broxterman
authors.forename: Bernard
authors.initials: B
authors.lastname: Kaptein
authors.forename: Cristina
authors.initials: C
authors.lastname: Peggion
authors.forename: Fernando
authors.initials: F
authors.lastname: Formaggio
authors.forename: Claudio
authors.initials: C
authors.lastname: Toniolo
mesh_terms: D002942:Circular Dichroism / Q000379:methods*; D003198:Computer Simulation; D005456:Fluorescent Dyes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism
chemical_list: D005456:Fluorescent Dyes; D010455:Peptides; D011166:Porphyrins