title: A spectroscopic study of the conformation of poly d(G-C).poly d(G-C) modified with the carcinogenic 2-aminofluorene.
abstract: The conformational properties of both the B- and Z-form helix of the 2-aminofluorene (AF) modified synthetic polynucleotide poly d(G-C).poly d(G-C) were extensively studied with a variety of optical techniques (UV absorbance, linear dichroism, circular dichroism and fluorescence spectroscopy). The spectroscopic results show, that: (i) the presence of the AF adduct in poly d(G-C).poly d(G-C) facilitates the conversion of the right-handed B-form polynucleotide to the left-handed Z-type poly d(G-C).poly d(G-C) duplex; (ii) in B- as well as in Z-form poly d(G-C).poly d(G-C)-AF the carcinogenic residue is situated in a specific and ordered complex with the DNA, in which the AF chromophore is significantly immobilized and the long axis of the fluorene ring system is positioned in a parallel mode to the DNA base planes; (iii) in B-type poly d(G-C).poly d(G-C)-AF the carcinogenic residue exhibits strong stacking interactions with the adjacent DNA bases, which are coupled to an important destabilization of the AF-containing B-duplex; (iv) in contrast to the B-form complex, the AF-containing Z-type DNA is highly stabilized and a remarkable reduction of the AF-base interactions is observed; (v) in Z-form poly d(G-C).poly d(G-C)-AF the AF chromophore resides at a medium-exposed position. The combined data support a conformational model, in which the planar AF is inserted in the B-type polynucleotide helix, while the carcinogenic residue in the Z-form poly d(G-C).poly d(G-C)-AF structure is placed in an outside position.
authors: Department of Biophysics, Free University, De Boelelaan, The Netherlands.
authors: L P
authors: LP
authors: van Houte
authors: J G
authors: JG
authors: Westra
authors: J
authors: J
authors: Retèl
authors: R
authors: R
authors: van Grondelle
mesh_terms: D002273:Carcinogens; D002942:Circular Dichroism; D005449:Fluorenes; D009690:Nucleic Acid Conformation; D011089:Polydeoxyribonucleotides; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002273:Carcinogens; D005449:Fluorenes; D011089:Polydeoxyribonucleotides; C019530:poly(dC-dG); C012177:2-aminofluorene