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Raman spectra obtained by UV laser excitation above 260 nm are contaminated by spectrally overlapping UV‐excited fluorescence. Here, we demonstrate a picosecond UV Kerr‐gated Raman spectroscopy setup to suppress the fluorescence in Raman spectra excited by 280 nm laser pulses. Specifically, we use a model sample that consists of acetonitrile contaminated by a small amount of toluene for generating UV‐excited fluorescence. We were able to acquire a Raman spectrum of acetonitrile by suppressing the UV‐excited fluorescence of toluene by the action of a 1‐mm thick fused silica‐based UV Kerr gate operated by 1030 nm, ~1 ps gating pulses. These results also indicate the challenges that must be overcome in the future for realizing UV‐fluorescence‐free UV resonance Raman (UVRR) spectroscopy studies of molecules exhibiting electronic resonances around 280 nm using laser excitation wavelengths right at or close to this resonance. [ABSTRACT FROM AUTHOR]

Ultraviolet resonance Raman (UVRR) scattering is a highly sensitive and selective vibrational spectroscopic technique with a broad range of applications from polyaromatic hydrocarbons (PAHs) to biomolecular systems (peptides/proteins and nucleic acids) and catalysts. The interpretation of experimental UVRR spectra is not as straightforward as in purely vibrational Raman scattering (Placzek approximation) due to the involvement of higher lying electronic states and vibronic coupling. This necessitates the comparison with theoretical UVRR spectra computed by electronic structure calculations. Anthracene is an ideal model system for such a comparison between experiment and theory because it is rigid, symmetric, and of moderate size. By taking into account Herzberg–Teller contributions including Duschinsky effects, bulk solvent effects, and anharmonic contributions, a good qualitative agreement close to the resonance condition is achieved. The present study shows that within the framework of time‐dependent density functional theory (TD‐DFT), a general and robust approach for the analysis and interpretation of resonance Raman spectra of medium‐ to large‐size molecules is available. [ABSTRACT FROM AUTHOR]

Ultraviolet resonance Raman (UVRR) spectroscopy is a powerful vibrational spectroscopic technique for the label-free monitoring of molecular recognition of peptides or proteins with supramolecular ligands such as guanidiniocarbonyl pyrroles (GCPs). The use of UV laser excitation enables Raman binding studies of this class of supramolecular ligands at submillimolar concentrations in aqueous solution and provides a selective signal enhancement of the carboxylate binding site (CBS). A current limitation for the extension of this promising UVRR approach from peptides to proteins as binding partners for GCPs is the UV-excited autofluorescence from aromatic amino acids observed for laser excitation wavelengths >260 nm. These excitation wavelengths are in the electronic resonance with the GCP for achieving both a signal enhancement and the selectivity for monitoring the CBS, but the resulting UVRR spectrum overlaps with the UV-excited autofluorescence from the aromatic binding partners. This necessitates the use of a laser excitation

Recent advances in optical and spectroscopic technologies have enabled a plethora of Raman spectrometers that are suitable for studies of protein pharmaceuticals. Highly sensitive Raman spectrometers have overcome the handicap of the fundamentally weak Raman effect that hampered their applications to protein pharmaceuticals in the past. These Raman spectrometers can now routinely measure protein therapeutics at the low concentration of 1 mg/mL, which is on par with other spectroscopic methods such as CD, fluorescence and FTIR spectroscopies. In this article, various Raman techniques that can be used for protein pharmaceutical studies are reviewed. Novel Raman marker of proteins discovered from fundamental studies of protein complexes are examined along with established Raman spectra and structure correlations. Examples of Raman spectroscopic studies of protein pharmaceuticals are demonstrated. Future applications of Raman spectroscopy to protein pharmaceuticals are discussed. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 2861–2878, 2007 [ABSTRACT FROM AUTHOR]