Structural polymorphism

Alexandridis P, Olsson U and Lindman B 1997 Structural polymorphism of amphiphilic copolymers Six lyotropic liquid crystalline and two solution phases in a poly(oxybutylene)-poly(oxyethylene)-water-xylene system Langmuir 23-34... 

S. Ezrahi, E. Wachtel, A. Aserin, N. Garti. Structural polymorphism in a four component nonionic microemulsion. J Coll Interface Sci 797 277-290, 1997. 

Phospholipids are amphiphilic compoimds with high surface activity. They can significantly influence the physical properties of emulsions and foams used in the food industry. Rodriguez Patino et al. (2007) investigated structural, morphological, and surface rheology of dipalmitoylpho-sphatidylcholine (DPPC) and dioleoyl phosphatidylcholine (DOPC) monolayers at air-water interface. DPPC monolayers showed structural polymorphisms at the air-water interface as a function of surface pressure and the pH of the aqueous phase (Fig. 6.18). DOPC monolayers showed a... 

Arranz, M. J., Collier, D. A., Munro, J. etal. (1996). Analysis of a structural polymorphism in the 5-HT2A receptor and clinical response to clozapine. Neurosci. Lett. 217, 177-8. 

Furthermore, it is often possible to extract from the structural analysis of solid solvates a significant information on solvation patterns and their relation to induced structural polymorphism. An interesting illustration has been provided by crystal structure determinations of solvated 2,4-dichloro-5-carboxy-benzsulfonimide (5)35). This compound contains a large number of polar functions and potential donors and acceptors of hydrogen bonds and appears to have only a few conformational degrees of freedom associated with soft modes of torsional isomerism. It co-crystallizes with a variety of solvents in different structural forms. The observed modes of crystallization and molecular conformation of the host compound were found to be primarily dependent on the nature of the solvent environment. Thus, from protic media such as water and wet acetic acid layered structures were formed which resemble intercalation type compounds. 

A promoter polymorphism at bp -361 [49, 50] affects promoter function. The G-allele is more active in H4IIE-C3 cells than the A-allele [49]. In the Japanese population, this polymorphism is in linkage disequilibrium with the structural polymorphism the inactive variant ALDH2 2 allele is more frequently associated with the G promoter allele [50]. Unlike the structural polymorphism, this promoter polymorphism is found in a wide variety of populations, including North-Ameri-can Caucasians and African Americans [49,50]. This makes it of possible pharma-cogenetic importance in affecting the risk for alcoholism or alcohol effects. 

A. E. Eckhardt, C. S. Timpte, A. W. DeLuca, and R. L. Hill, The complete cDNA sequence and structural polymorphism of the polypeptide chain of porcine submaxillary mucin, J. Biol. Chem., 272 (1997) 33204—33210. 

A large number of compounds of pharmaceutical interest are capable of being crystallized in either more than one crystal lattice structure (polymorphs), with solvent molecules included in the crystal lattice (solvates), or in crystal lattices that combine the two characteristics (polymorphic solvates) [122,123]. A wide variety of structural explanations can account for the range of observed phenomena, as has been discussed in detail [124,125]. The pharmaceutical implications of polymorphism and solvate formation have been recognized for some time, with solubility, melting point, density, hardness, crystal shape, optical and electrical properties, vapor pressure, and virtually all the thermodynamic properties being known to vary with the differences in physical form [126]. 

Structural polymorphism has been already reported as a peculiar solid-solid phase transition with a large spectral shift in the cast film of CgAzoCioN+ Br (chapter 4). The type 1 spectrum was thermally transformed to the type VI spectrum and then backed to the type I by the isothermal moisture treatment. The reversible spectral change between the type I and VI is a good experimental evidence of Okuyama s prediction on the molecular packing. Since the type VI state is assumed to be a metastable state, the isothermal phase transition to the type I state is expected to be induced by some external stimuli. Water molecules adsorbed to cast bilayer films might act as an accelerator of the phase transition. 

Heise, H., Hoyer, W., Becker, S., Andronesi, O. C., Riedel, D., and Baldus, M. (2005). Molecular-level secondary structure, polymorphism, and dynamics of full-length alpha-synuclein fibrils studied by solid-state NMR. Proc. Natl. Acad. Sd. USA 102,... 

Particle size distribution Phase volume fraction Lamellar structure Polymorphism... 

One proposed material is BiV04 in its monoclinic (scheelite structure) polymorph, which shows a good photocatalytic activity for 02 evolution in the presence of Ag+ (9% quantum yield at 450 nm) [125]. The band gap of this vanadate... 

R. Lieckfeldt, J. Villalain, J. C. Gomez-Fernandez, and G. Lee. Diffusivity and structural polymorphism in some model stratum corneum lipid systems. Biochim. Biophys. Acta Biomembr. 1150 182-188 (1993). 

N. Yamada, T. Nagase, N. OzaM, O. Ohara, N. Ishida, M. Okawa, K. Takahashi, and T. Yamauchi, Association of structural polymorphisms in the human periods gene with delayed sleep phase syndrome. EMBO Rep. 2, 342-346 (2001). 

DNA is a structurally polymorphic macromolecule which, depending on nucleotide sequence and environmental conditions, can adopt a variety of conformations. The double helical structure of DNA (dsDNA) consists of two strands, each of them on the outside of the double helix and formed by alternating phosphate and pentose groups in which phosphodiester bridges provide the covalent continuity. The two chains of the double helix are held... 

Camacho F, Cilio M, Guo Y et al 2001 Human casein kinase Idelta phosphorylation of human circadian clock proteins period 1 and 2. FEES Lett 489 159-165 Delaunay F, Thisse C, Marchand O, Laudet V, Thisse B 2000 An inherited functional circadian clock in zebrafish embryos. Science 289 297-300 Dunlap J 1998 Circadian rhythms. An end in the beginning. Science 280 1548-1549 Ebisawa T, Uchiyama M, Kajimura N et al 2001 Association of structural polymorphisms in the human period3 gene with delayed sleep phase syndrome. EMBO Rep 2 342-346 Edery I, Zwiebel LJ, Dembinska ME, Rosbash M 1994 Temporal phosphorylation of the Drosophila period protein. Proc Natl Acad Sci USA 91 2260-2264 Ishida N, Kaneko M, AUada R 1999 Biological clocks. Proc Natl Acad Sci USA 96 8819-8820... 

The double hehx of the DNA can only to a first approximation be considered a linear, rod-like structure with the typical coordinates of B-DNA. Actually DNA possesses considerable flexibility and conformational variability. The flexibihty and structural polymorphism of DNA are prerequisites for many of the regulatory processes on the DNA level (review Harrington, 1994 Alleman and Egli, 1997). Local deviation from the classical B-structure of DNA, as well as bending of the DNA, are observed in many protein-DNA complexes. 

Kaolins. The kaolin minerals include kaolinite. dickite. and nacrite which all have composition AUOi 2 SiO 2 FLO halloysite (7 At. AGO, 2 SiO, 2 H.O and halfoysile (10 A). Al 0, 2 SiO 4 H 0 The struclural formulas for kaolinite and halloysite tIO At. which are shown in Figure I, are AbSiaOiotOH)). and AljSi.iO, i(OH) -4 H,(). respectively. The so-called fire day mineral is a h-axis disordered kaolinite halloysite (7 A) and halloysite (10 A) are disordered along both the a- and h-Mcs Indeed, most variations in the kaolin group originate as structural polymorphs, related to variations in layer slacks. 

Gonzales, L., Jr., Brown, R. A., Richardson, D., and Alber, T. (1996a). Crystal structures of a single coiled-coil peptide in two oligomeric states reveal the basis for structural polymorphism. Nat. Struct. Biol. 3, 1002-1010. 

In a recent extensive study, the structural polymorphism of DNA/RPR120535 complexes has been studied by X-ray diffraction and cryo-electron microscopy. Monovalent salts and temperature effects have been analyzed. Depending on the treatment applied to the lipid solution prior to DNA addition, two types of... 

The majority of all APIs manufactured demonstrate structural polymorphism. In order to formulate a drug product that is physically and chemically stable, the formulation team must identify the most thermodynamically stable polymorph of the API. By identifying the proper polymorph, the patient s need for a drug product with reproducible bioavailability during the course of typical and atypical shelf-life conditions will be met. This section will review the use of spectroscopic techniques for identifying polymorphism of APIs during API crystallization and formulation. For a more comprehensive discussion of polymorphism the reader is directed to a work by Singhal85 and references cited therein. 

Arias B, Arranz MJ, Gasto C, et al. Analysis of structural polymorphisms and C-1018G promoter variant of the 5-HT(lA) receptor gene as putative risk factors in major depression. Mol Psychiatry 2002 7(9) 930-932. 

---