Side chains, Raman optical activity

Vibrational Raman optical activity of biomolecules, including carbohydrates, has been reviewed (23 refs). l A general procedure for assigning both relative and absolute configuration to multiple stereocentres in acyclic aminopolyols based on application of the exiton chirality method is presented. The method has been applied to the side chain aminopolyol of a natural bacterial-derived terpenoid derivative. ... 

Vibrational spectroscopy is an important tool to obtain information about the secondary structure of proteins [827]. The ability to relate protein conformations to infrared vibrational bands was established very early in the pioneering work of Elhot and Ambrose before any detailed X-ray results were available [828]. Vibrational circular dichroism (VCD) provides sensitive data about the main chain conformation [829, 830]. The Raman optical activity (ROA) signal results from sampling of different modes but is especially sensitive to aromatic side chains [831, 832]. A theoretical prediction for the ROA phenomenon was developed by Barron and Buckingham [833, 834], and the first ROA spectra were measured by Barron, Bogaard and Buckingham [835, 836]. First ab initio predictions were provided by Polavarapu [837]. In 2003, Jalkanen et al. showed that DPT approaches in combination with explicit water molecules and a continuum model reproduce the experimental spectra much better [838]. DFT-based approaches to VCD spectra were, for example, pioneered by Stephens et al. [839]. To extract the local structural information provided by ROA, Hudecova et al. [721] developed multiscale QM/MM simulation techniques. 

Hudecova J et al (2010) Side chain and flexibility contributions to the Raman optical activity spectra of a model cyclic hexapeptide. J Phys Chem A 114 7642-7651... 

Low Frequency Observations for Amorphous Polymers. Many amorphous materials studied by Raman exhibit an extremely broad band in the low frequency region. This is true for polycarbonate, poly(methyl methacrylate), and polystyrene (58). Low frequency Raman bands can potentially provide much information regarding the density of states (directly related to the intensity distribution of the broad Raman active band) as well as anomalous behavior observed for the specific heat (58). Often the separation of main-chain and side-chain bands is important in modeling of specific heat, making careful band assignment extremely meaningful (136,137). This separation is analogous to inclusion of optical... 

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