Infrared spectroscopy of proteins.

This review deals with current concepts of vibrational spectroscopy for the investigation of protein structure and function. While the focus is on infrared (IR) spectroscopy, some of the general aspects also apply to Raman spectroscopy. Special emphasis is on the amide I vibration of the polypeptide backbone that is used for secondary-structure analysis. Theoretical as well as experimental aspects are covered including transition dipole coupling. Further topics are discussed, namely the absorption of amino-acid side-chains, 1H/2H exchange to study the conformational flexibility and reaction-induced difference spectroscopy for the investigation of reaction mechanisms with a focus on interpretation tools.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033583502003815

What vibrations tell us about proteins

Polycyclic Hydrocarbons Vol. 1. Pp. xxvi + 487. 126S. (With a chapter on carcinogenesis by Regina Schoental.) Vol. 2. Pp. lvii + 487. 140s. By E. Clar. (London and New York: Academic Press; Berlin: Springer-Verlag, 1964.)

Polycyclic Aromatic Hydrocarbons

Amino acid side chains play fundamental roles in stabilising protein structures and in catalysing enzymatic reactions. These fields are increasingly investigated by infrared spectroscopy at the molecular level. To help the interpretation of the spectra, a review of the infrared absorption of amino acid side chains in H(2)O and 2H(2)O is given. The spectral region of 2600-900cm(-1) is covered.

The infrared absorption of amino acid side chains.

Raman spectroscopy is a potentially important clinical tool for real-time diagnosis of disease and in situ evaluation of living tissue. The purpose of this article is to review the biological and physical basis of Raman spectroscopy of tissue, to assess the current status of the field and to explore future directions. The principles of Raman spectroscopy and the molecular level information it provides are explained. An overview of the evolution of Raman spectroscopic techniques in biology and medicine, from early investigations using visible laser excitation to present-day technology based on near-infrared laser excitation and charge-coupled device array detection, is presented. State-of-the-art Raman spectrometer systems for research laboratory and clinical settings are described. Modern methods of multivariate spectral analysis for extracting diagnostic, chemical and morphological information are reviewed. Several in-depth applications are presented to illustrate the methods of collecting, processing and analysing data, as well as the range of medical applications under study. Finally, the issues to be addressed in implementing Raman spectroscopy in various clinical applications, as well as some long-term directions for future study, are discussed.

/pdf/prospects-for-in-vivo-raman-spectroscopy-1fkovf1b8p.pdf

Prospects for in vivo Raman spectroscopy.

The Raman scattering cross sections of vibrations of SO4−2, NO3−, ClO4−, and CH3CN have been determined between 220–640 nm. The cross sections of the symmetric stretching vibrations of SO4−2 and ClO4− as well as the 918 cm−1 C–C stretching vibration of CH3CN display almost a ν4 excitation frequency dependence. The intensity of the 2249 cm−1 C≡N stretching vibration increases somewhat faster than ν4, but significantly slower than that which would be expected if a dipole allowed C≡N π→π* transition at ∼150 nm dominated the Raman intensity. The intensity of the NO3− symmetric stretch increases with a frequency dependence close to that expected from an Albrecht A term contribution from the ∼200 nm π→π* transition. The fact that the 981 cm−1 SO4−2, 932 cm−1 ClO4−, and 918 cm−1 CH3CN vibrations show essentially only ν4 intensity dependencies indicates that no particular dipole allowed transition dominates the preresonance Raman intensities. These results suggest that conventional preresonance Raman expressions ...

Wavelength dependence of the preresonance Raman cross sections of CH3CN, SO42−, ClO4−, and NO3−

UV resonance Raman excitation profiles of the aromatic amino acids

The first ultraviolet resonance Raman measurements of a coal liquid are reported. The spectra detail the presence of numerous polycyclic aromatic hydrocarbons with ring systems similar to those of naphthalene, fluorene, phenanthrene, pyrene, and triphenylene . The ultraviolet resonance Raman measurements of this highly complex sample show no significant interference from fluorescence. The lack of fluorescence interference and the high selectivity indicate that ultraviolet resonance Raman spectroscopy is a powerful new technique for characterizing highly complex samples and mixtures.

https://science.sciencemag.org/content/sci/225/4659/311.full.pdf

Raman spectroscopy of a coal liquid shows that fluorescence interference is minimized with ultraviolet excitation

Ultraviolet resonance Raman characterization of photochemical transients of phenol, tyrosine, and tryptophan

The design and construction of a new UV resonance Raman spectrometer continuously tunable between 217–750 nm are described. The excitation source is based on a YAG laser which is frequency doubled or tripled to pump a dye laser. UV light is generated by nonlinear frequency doubling and mixing of the dye laser output or doubled output with the 1.06‐μm YAG fundamental. The detection system utilizes an intensified Reticon multichannel array. Commercially available monochromators are modified to make them useful for UV resonance Raman spectroscopy. Some sampling methodologies important for UV resonance Raman measurements are described. Examples of the sensitivity of UV resonance Raman spectroscopy are illustrated.

Craig R. Johnson

Papers

Wavelength dependence of the preresonance Raman cross sections of CH3CN, SO42−, ClO4−, and NO3−

UV resonance Raman excitation profiles of the aromatic amino acids

Raman spectroscopy of a coal liquid shows that fluorescence interference is minimized with ultraviolet excitation

Ultraviolet resonance Raman characterization of photochemical transients of phenol, tyrosine, and tryptophan

Development of a new UV resonance Raman spectrometer for the 217–400‐nm spectral region