Raman spectroscopy conformational analysis

Raman spectroscopy is considered a complementary technique to FTIR for the conformational analysis of chromatographic materials. Raman spectroscopy relies on... 

In addition, any rational approach to peptide hormone and neurotransmitter design must ultimately depend on the application of physical-chemical principles of conformation and structure, the use of various spectroscopic methods (especially nuclear magnetic resonance, circular dlchrolsm, and Raman spectroscopies. X-ray analysis where possible, etc.), and an understanding of the nature of a hormone-receptor Interaction In physical-chemical terms. Here again the use of conformatlonally restricted peptide structures Is critical (, 2. Recently we have... 

Conformational analysis can be performed using a variety of methods.1161 Most important are X-ray analysis and NMR spectroscopic techniques, which allow detailed insights into the topology of the peptides. NMR combined with molecular dynamic calculations provides the spatial structure of the peptide, but also its dynamics in solution.13643491 Additional information can be obtained from FTIR,15,4521 CD,151,53-551 or Raman spectroscopy. 56,571 The results derived from such conformational analysis of cyclic peptides have a considerable impact on the study of the bioactive conformations of peptides and on the design of cyclic peptides as proteinomimetics.124,58,59,6301... 

Raman spectroscopy is a related vibrational spectroscopic method. It has a different mechanism and therefore can provide complementary information to infrared absorption for the peptide protein conformational structure determination and some multicomponent qualitative and/or quantitative analysis (Alix et al. 1985). 

It may be concluded, from the analysis of the Raman results, that the information provided by Raman spectroscopy is, in essence, similar to that of infrared spectroscopy. The exploitation of the data, namely, the frequencies and intensities due to the molecular vibrations, is of a certain benefit in giving some insight as to the conformations of carbohydrates, and their interactions with the environment. As laser-Raman spectroscopy is applicable to solids, as well as to aqueous solutions, the linear relationship between Raman intensities and mass concentrations, and the specificity and high quality of the spectra experimentally obtained, make this technique particularly promising in investigations of the chemistry and biochemistry of carbohydrates. 

Observations were made of lipid-protein phases in which the structure is determined mainly by the protein. Raman spectroscopy is a useful method for structure analysis of such phases. The structures described above were analyzed successfully by an x-ray diffraction technique. Lipid-protein complexes, however, are often amorphous, and alternative methods to study their structures are therefore needed. It was demonstrated that Raman spectroscopy can be used to obtain structural information about lipid-protein interaction (16, 17). It is thus possible to determine the conformation as well as the type of environment of the lipid molecules. With the protein, interpretation is more complicated. It is usually possible to determine whether the complex has the same protein conformation as the component used in the preparation, or, if a change occurs, it may be possible to correlate it with denaturation of the pure protein. For complexes formed by long-chain alkyl phosphates and insu-... 

Fourier-Transform Infrared (FTIR) spectroscopy as well as Raman spectroscopy are well established as methods for structural analysis of compounds in solution or when adsorbed to surfaces or in any other state. Analysis of the spectra provides information of qualitative as well as of quantitative nature. Very recent developments, FTIR imaging spectroscopy as well as Raman mapping spectroscopy, provide important information leading to the development of novel materials. If applied under optical near-field conditions, these new technologies combine lateral resolution down to the size of nanoparticles with the high chemical selectivity of a FTIR or Raman spectrum. These techniques now help us obtain information on molecular order and molecular orientation and conformation [1],... 

Infrared (IR) and Raman spectroscopy (71PMH(4)265) are of limited value in the conformational analysis of more complex molecules, since it is usually impossible to identify the bands, and to distinguish between fundamentals and overtones and combination tones. 

UV resonance Raman spectroscopy (UVRR), Sec. 6.1, has been used to determine the secondary structure of proteins. The strong conformational frequency and cross section dependence of the amide bands indicate that they are sensitive monitors of protein secondary structure. Excitation of the amide bands below 210 nm makes it possible to selectively study the secondary structure, while excitation between 210 and 240 nm selectively enhances aromatic amino acid bands (investigation of tyrosine and tryptophan environments) (Song and Asher, 1989 Wang et al., 1989, Su et al., 1991). Quantitative analysis of the UVRR spectra of a range of proteins showed a linear relation between the non-helical content and a newly characterized amide vibration referred to as amide S, which is found at 1385 cm (Wang et al., 1991). 

In view of the progress to date, it is clear that IR and Raman spectroscopy, together with normal-mode analysis, will have a major contribution to make to the detailed study of conformation in polypeptides and proteins. 

Common methods used to characterize drugs and excipients are infrared (IR) and Raman spectroscopy. These techniques are sensitive to the structure, conformation, and environment of organic compounds. Because of this sensitivity, they are useful characterization tools for pharmaceutical crystal forms. Qualitative as well as quantitative analysis can be performed with both techniques. 

Fluconazole Two different polymorphic forms of fluconazole were identified by Raman spectroscopy. Spectral assignments were made for each form, and the conformational data compared to the crystallographic and thermal analysis data. 63... 

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