UV resonance Raman study of platinum binding to guanine in mono‐ and di‐nucleotides

Abstract

Ultraviolet resonance Raman (UVRR) spectra, with 240 and 218 nm excitation, are reported for complexes of cis-(NH3),Pt2+ with dGMP (2-deoxyguanosine 5'-monophosphate) having H or D at C-8. Previously reported UVRR effects of P t 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 P t 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 P t -+ G metal-ligand chargetransfer transition. Because bands showing large frequency shifts on P t binding are selectively enhanced by this transition, 218 nm is the best wavelength for monitoring P t binding to G in UVRR spectra. Even a t 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)* + (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-Z-endo) sugar conformations, and also intensity alterations which may be associated with the 'head-to-head' arrangement of the Pt-bound G residues.

An Ultraviolet Resonance Raman Spectroscopic Study of Cisplatin and Transplatin Interactions with Genomic DNA

“…These observations are consistent with previous Raman results in the literature. 32,37 In the spectrum of dAMP, the major impact of cisplatin is an intensity decrease of the Raman bands at 1484 and 1341 cm −1 . Again, the bands arise from aromatic ring modes involving the N7 atom (Table S1).…”

“…Assignments of their Raman bands are summarized in Table S1, as derived from previous results. 27,29,31,32,37 The UVRR spectra of the four nucleotides are distinguishable (Figure 3). Notably, the UVRR bands of dGMP and dAMP show the strongest resonance enhancement with the 244 nm excitation.…”

Investigation of an unnatural amino acid for use as a resonance Raman probe: detection limits and solvent and temperature dependence of the νCN band of 4‐cyanophenylalanine

“…$\left(\frac{I_N}{I_S}\right)$ is the peak height ratio, ν 0 is the excitation wavelength (cm −1 ), ν N and ν S are the wavenumbers (cm −1 ) of the sample and standard, respectively, $\left(\frac{C_S}{C_N}\right)$ is the concentration ratio, and A N , A S and A 0 are the relative absorption at the sample, standard and laser excitation wavelenths. The Raman cross section of the CN − band at 2080 cm −1 was calculated using the Raman cross sections of ClO 4 reported by Perno et al 25. as the standard, using interpolated values when necessary.…”

“…I N I S is the peak height ratio, 0 is the excitation wavelength (cm 1 ), N and S are the wavenumbers (cm 1 ) of the sample and standard, respectively, C S C N is the concentration ratio, and A N , A S and A 0 are the relative absorption at the sample, standard and laser excitation wavelengths. The Raman cross-section of the CN band at 2080 cm 1 was calculated using the Raman cross-sections of ClO 4 reported by Perno et al 25 as the standard, using interpolated values when necessary. The values determined for the CN band at 2080 cm 1 (Supporting Informations, Table S1) were used to determine the Raman cross-sections of the PheCN C N mode at 2237 cm 1 and the PheCN 8a phenyl ring mode at 1611 cm 1 .…”

Tunable kHz Deep Ultraviolet (193–210 nm) Laser for Raman Applications

“…Ϫ cross-section down to 193 nm in aqueous mixtures, using an SO 4 2Ϫ crosssection interpolated from the measurements of Fodor et al 22 Cross-sections obtained from this study are slightly lower than the values reported earlier by Perno et al (Table I). 23 The solid curve (Fig. 4) is a fit to the data using Eq.…”