Polymorph identification

Haff LA, Smirnov IP. Single-nucleotide polymorphism identification assays using a thermostable DNA polymerase and delayed extraction MALDI-TOF mass spectrometry. Genome Res 1997 7 378-388. 

Lyamichev, V., et al., Polymorphism identification and quantitative detection of genomic DNA by invasive cleavage of oligonucleotide probes. Nat Biotechnol, 1999. 17(3) p. 292-6. 

Victor Lyamichev, Andrea L. Mast, Jeff G. Hall, James R. Prudent, Michael W. Kaiser, Tsetska Takova, Robert W. Kwiatkowski, Tamara J. Sander, Monika de Arruda, David A. Arco, Bruce P. Neri and Mary Ann D. Brow, Polymorphism identification and quantitative detection of genomic DNA by invasive cleavage of oligonucleotide probes. Nature Biotechnology, 17 (1999), 292-296. 

FTIR and Raman spectroscopy are frequently used to characterize polymorphs. Both the molecular conformation and the crystal packing may lead to differences in the FTIR spectra of polymorphs the differences are more pronounced for compounds capable of hydrogen bonding. Characteristic shifts in C=0, N-H, and O-H stretching frequencies often lead to unequivocal polymorphic identification. Differences in fine structure and in the positions and intensities of IR bands enabled seven crystalline forms of the steroid prasterone 3 to be distinguished."" The presence of characteristic absorption bands due to included solvent molecules allows ready distinction between polymorphs and pseudopolymorphs. 

Tournel G, Cauffiez C, Leelere J, Billaut-Laden I, Allorge D, Chevalier D, Migot-Nabias F, Kenani A, Broly F, Lo-Guidice J (2007) CYP2F1 genetic polymorphism identification of interethnic variations. Xenobiotica 37 1433-1438... 

A significant advantage of the PLM is in the differentiation and recognition of various forms of the same chemical substance polymorphic forms, eg, brookite, mtile, and anatase, three forms of titanium dioxide calcite, aragonite and vaterite, all forms of calcium carbonate Eorms I, II, III, and IV of HMX (a high explosive), etc. This is an important appHcation because most elements and compounds possess different crystal forms with very different physical properties. PLM is the only instmment mandated by the U.S. Environmental Protection Agency (EPA) for the detection and identification of the six forms of asbestos (qv) and other fibers in bulk samples. 

In the identification of different polymorphs in polymers the FTIR technique presents, with respect to the diffraction techniques, the advantage of easier and more rapid measurements. In particular, the high speed of the measurements allows to study the polymorphic behavior under dynamic conditions. As an example let us recall the study of the transition from the a toward the P form of PBT induced by tensile stresses, evaluated by quantitative analysis of the infrared spectra [83],... 

Single resonances are instead observed for the P form of i-PP, for which these kinds of pairs of helices are not present. However, these splittings of the NMR signals are not particularly useful for the identification of the various polymorphs of i-PP, since they are small (being intermolecular in origin) and since they are not evident in not well-crystallized a form samples [117, 119]. 

Identification of proteins that bind to Z-DNA added one further step to the establishment of the presence of Z-DNA in vivo and its possible biological role. Herbert and Rich [22] demonstrated an in vitro assay system where one type of double-stranded RNA adenosine deaminase, called DRAD-binding Z-DNA. There are evidences that topoisomerase II from Drosophila, hiunan and calf thymus recognizes a number of DNA shapes, including Z-DNA [34,35]. Bloomfield and coworkers [36] have found that the condensation of plasmids is enhanced by Z-DNA conformation in d(CG)n repeats. The information related to B-Z transition [31], the effect of ligands on it [28,29] and X-ray crystal structure data [37,38] appear to suggest that the possible biological role of this polymorphic form of DNA will be soon established. 

R. Sanders, M. Alt, K, Groppe, T. Boiler, and A. Wiemken, Identification of ribosomal DNA polymorphisms among and within spores of the Glomules application to studies on the genetic diversity of arbuscular mycorrhizal fungal communities. New Phytol. /30 419 (1995). 

Functional roles for chemokines and receptors have also been obtained through identification and analysis of polymorphisms present in a handful of these genes. As discussed previously, individuals harboring the delta-32 mutation of CCR5 are significantly resistant to HIV-1 infection. Polymorphisms in... 

Applications The general applications of XRD comprise routine phase identification, quantitative analysis, compositional studies of crystalline solid compounds, texture and residual stress analysis, high-and low-temperature studies, low-angle analysis, films, etc. Single-crystal X-ray diffraction has been used for detailed structural analysis of many pure polymer additives (antioxidants, flame retardants, plasticisers, fillers, pigments and dyes, etc.) and for conformational analysis. A variety of analytical techniques are used to identify and classify different crystal polymorphs, notably XRD, microscopy, DSC, FTIR and NIRS. A comprehensive review of the analytical techniques employed for the analysis of polymorphs has been compiled [324]. The Rietveld method has been used to model a mineral-filled PPS compound [325]. 

Spurlock, G., Helis, A., Holmas, P. etal. (1998). A family based association study of T 102C polymorphism in 5HT2A and schizophrenia plus identification of new polymorphisms in the promoter. Mol. Psychiatry, 3, 42-9. 

Zill, P., Engel, R., Baghai, T. C. etal. (2002). Identification of a naturally occurring polymorphism in the promoter region of the norepinephrine transporter and analysis in major depression. Neuropsychopharmacol, 26, 489-93. 

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