UV resonance Raman spectroscopy of DNA and protein constituents of viruses: Assignments and cross sections for excitations at 257, 244, 238, and 229 nm

Abstract

Ultraviolet resonance Raman (UVRR) spectra of H2O and D2O solutions of the nucleoside (dA, dG, dC, dT) and aromatic amino acid (Phe, Trp, Tyr) constituents of DNA viruses have been obtained with laser excitation wavelengths of 257, 244, 238, and 229 nm. Using the 981 cm-1 marker of Na2SO4 as an internal standard, Raman frequencies and scattering cross sections were evaluated for all prominent UVRR bands at each excitation wavelength. The results show that UVRR cross sections of both the nucleosides and amino acids are strongly dependent on excitation wavelength and constitute sensitive and selective probes of the residues. The results provide a library of UVRR marker bands for structural analysis of DNA viruses and other nucleoprotein assemblies.

A new single grating spectrograph for ultraviolet Raman scattering studies

“…Although the dA Raman spectrum obtained by Wen and Thomas, 91 also utilizing 257-nm excitation evidently exhibits a better SNR than our dA spectrum displayed in Fig. 6, it is difficult to compare these two dA DUV Raman spectra semiquantitatively, since the acquisition time of the literature spectrum, which has also been background subtracted, has unfortunately not been disclosed.…”

“…Initial efforts to obtain Raman spectra from an aqueous 530 µM dA solution, as published by Wen and Thomas, 91 proved unsuccessful because of the strong self-absorption of both the incident laser and the Raman scattered radiation. Subsequent dilution to ca 32 µM allowed a Raman spectrum of dA to be measured successfully with the dominant band observed at ¾1336 cm 1 , which has been assigned to a C5N7 and N7C8 stretching mode of the purine ring, 91 being positioned between the two relatively broad water signals occurring at ¾740 and ¾1620 cm 1 at the left-and right-hand side of the spectrum (the lower wavenumber signal may be interpreted as arising from symmetric and antisymmetric stretching coordinates of the water hydrogen bonds 92 ). The origin of the relatively sharp signal observed at ¾1181 cm 1 and indicated by an asterisk remains unclear at present but, on account of its shape, arises most likely from a laser plasma line (occurring at 530.58 nm in air), which has not been fully suppressed so that it still features prominently in this relatively weak dA Raman spectrum.…”

“…6, it is difficult to compare these two dA DUV Raman spectra semiquantitatively, since the acquisition time of the literature spectrum, which has also been background subtracted, has unfortunately not been disclosed. The relatively long acquisition time of 1 hour for the measurement of our dA Raman spectrum may therefore be rationalized by the relatively low dA concentration utilized, as compared with the approximately 17 times more concentrated solution used to obtain the literature dA reference spectrum, 91 the implementation of an optical system for focusing the incident laser radiation and the collection of backscattered Raman radiation, which appears to be nonideal for strongly absorbing samples within the resonant scattering regime. Radiation in the approximately cylindrical laser focal region with a length of ca 13.3 mm (vide infra) is strongly absorbed by the dA sample.…”

Rapid detection of microorganisms with nanoparticles and electron microscopy

“…Indeed, UVRR spectroscopy can successfully analyze proteins (Pimenov et al, 2005) and DNA (Wen and Thomas, 1998). By selectively exciting electrons of some functional groups, specific parts of macromolecules could be investigated by using different excitation wavelengths, and 229 nm has been chosen to provide excitation of resonance in the aromatic residues of proteins.…”

The quality is in the eye of the beholder: The perspective of FTIR and UV resonant Raman spectroscopies on extracted nucleic acids

“…[8,16] Numerous scientific manuscripts indeed report on the determination of spectral features of DNA and RNA strands. [16][17][18][19] However, most of the published works focus on the analysis of simplified systems, such as short chains of nucleic acids or commercial genomic DNA samples, for example, Salmon or Calf Thymus DNA. The two abovementioned samples are the only ones certified as high-quality materials, pure from other biomolecules and chemicals employed for their extraction, because they are provided as lyophilized sodium salts.…”