ISSN:
0377-0486
Schlagwort(e):
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
Ultraviolet resonance Raman UVRR spectra, with 240 and 218 nm excitation, are reported for complexes of cis-NH32Pt2+ with dGMP 2-deoxyguanosine 5′-monophosphate having H or D at C-8. Previously reported UVRR effects of Pt binding to G are confirmed and extended. Excitation profiles recorded throughout the UV region are reported, together with cross-sections for the perchlorate ion, used as an internal standard. The excitation profiles show strong losses in enhancement associated with Pt binding for most of the guanine G UVRR bands in resonance with the UV electronic transitions of G. Hypochromic effects are involved, associated with diminished transition dipole moments due to the N-7-bound Pt, as are changes in Franck-Condon products. A new, weak resonance is seen in the excitation profiles at ca 220 nm, and is attributed to a Pt → G metal-ligand chargetransfer transition. Because bands showing large frequency shifts on Pt binding are selectively enhanced by this transition, 218 nm is the best wavelength for monitoring Pt binding to G in UVRR spectra. Even at this wavelength, Raman contributions from uncomplexed G and also A tend to obscure the Pt-bound G spectrum, as shown by the spectra of the dinucleotides d(GpG) and d(ApG) complexed with Pt(dien)2+ (dien = diethylenetriamine), although a marker for Pt-bound G can still be detected. The 218 nm-excited spectrum of cis-Pt[d(GpG)N-7(1), N-7(2)] shows clear evidence of both N(C-3′-endo) and S(C-2′-endo) sugar conformations, and also intensity alterations which may be associated with the ‘head-to-head’ arrangement of the Pt-bound G residues.
Zusätzliches Material:
10 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jrs.1250190311
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