title: Co-ordination behaviour of nucleic acid bases against the Fe(I)(NO)-2 group in solution. I. Purines: ESR study.
abstract: The binding sites of purine bases in the presence of the Fe(I)(NO)-2 group were investigated on the basis of the nuclear hyperfine structure of the electron spin resonance spectra. Selective isotopic substitution with 15-NO was used to clarify co-ordindination. Coupling constants and different types of complexes were determined by means of computer-simulated ESR spectra. Comparison was made with the binding sites of nucleotides and it was concluded that N-7, in the imidazole ring, is the preferred binding site. A structure with two base molecules bonded to the iron atom was proposed. Finally 8-azaguanine, an antitumoral agent, was studied and the special behaviour of this antimetabolite was demonstrated in the biologically-interesting pH values.
mesh_terms: D001375:Azaguanine; D001665:Binding Sites; D004578:Electron Spin Resonance Spectroscopy; D006147:Guanine; D007042:Hypoxanthines; D007501:Iron; D008968:Molecular Conformation; D009566:Nitrates; D009690:Nucleic Acid Conformation; D011687:Purines; D013055:Spectrophotometry, Infrared; D013057:Spectrum Analysis; D014970:Xanthines
chemical_list: D007042:Hypoxanthines; D009566:Nitrates; D011687:Purines; D014970:Xanthines; D006147:Guanine; D007501:Iron; D001375:Azaguanine