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Protein and Peptide Letters 2016Knowledge of 3D structures of biological molecules plays a major role in both understanding important processes of life and developing pharmaceuticals. Among several... (Review)
Review
Knowledge of 3D structures of biological molecules plays a major role in both understanding important processes of life and developing pharmaceuticals. Among several methods available for structure determination, macromolecular X-ray powder diffraction (XRPD) has transformed over the past decade from an impossible dream to a respectable method. XRPD can be employed in biosciences for various purposes such as observing phase transitions, characterizing bulk pharmaceuticals, determining structures via the molecular replacement method, detecting ligands in protein-ligand complexes, as well as combining micro-sized single crystal crystallographic data and powder diffraction data. Studies using synchrotron and laboratory sources in some standard configuration setups are reported in this review, including their respective advantages and disadvantages. Methods presented here provide an alternative, complementary set of tools to resolve structural problems. A variety of already existing software packages for powder diffraction data processing and analysis, some of which have been adapted to large unit cell studies, are briefly described. This review aims to provide necessary elements of theory and current methods, along with practical explanations, available software packages and highlighted case studies.
Topics: Macromolecular Substances; Models, Molecular; Molecular Structure; Powder Diffraction; Synchrotrons; X-Ray Diffraction
PubMed: 26786768
DOI: 10.2174/0929866523666160120152839 -
Journal of Pharmaceutical Sciences Dec 2018Since the discovery of X-ray diffraction and its potential to elucidate crystal symmetry, powder X-ray diffraction has found diverse applications in the field of... (Review)
Review
Since the discovery of X-ray diffraction and its potential to elucidate crystal symmetry, powder X-ray diffraction has found diverse applications in the field of pharmaceutical sciences. This review summarizes significant achievements of the technique during various stages of dosage form development. Improved understanding of the principle involved and development of automated hardware and reliable software have led to increased instrumental sensitivity and improved data analysis. These advances continue to expand the applications of powder X-ray diffraction to emerging research fields such as amorphous systems, mechanistic understanding of phase transformations, and "Quality by Design" in formulation development.
Topics: Crystallization; Drug Compounding; Equipment Design; Lasers; Pharmaceutical Preparations; Phase Transition; Powder Diffraction; Small Molecule Libraries; Synchrotrons; X-Ray Diffraction
PubMed: 30145209
DOI: 10.1016/j.xphs.2018.08.010 -
Topics in Current Chemistry 2012Many important crystalline solids cannot be prepared as single crystals of suitable size and quality for structural characterization by conventional single-crystal X-ray... (Review)
Review
Many important crystalline solids cannot be prepared as single crystals of suitable size and quality for structural characterization by conventional single-crystal X-ray diffraction techniques and can instead be prepared only as microcrystalline powders. However, recent advances in techniques for determining crystal structures directly from powder X-ray diffraction data have created a unique opportunity for establishing structural properties of such materials. This chapter surveys the applications of powder X-ray diffraction across various aspects of structural and materials chemistry, focusing mainly on the opportunities that have emerged in recent years for carrying out complete crystal structure determination from powder X-ray diffraction data and giving particular emphasis to the case of molecular crystal structures. The current scope and future potential of powder X-ray diffraction as a strategy for crystal structure determination are discussed, and examples of applications across several disciplines of materials chemistry are presented.
Topics: Computer Simulation; Crystallization; Crystallography, X-Ray; Models, Molecular; Molecular Structure; Powder Diffraction; Powders; Protein Conformation
PubMed: 21952843
DOI: 10.1007/128_2011_251 -
Acta Crystallographica. Section C,... Feb 2022The crystal structure of cynarine monohydrate (systematic name: 1,3-bis{[(E)-3-(3,4-dihydroxyphenyl)prop-2-enoyl]oxy}-4,5-dihydroxycyclohexane-1-carboxylic acid...
The crystal structure of cynarine monohydrate (systematic name: 1,3-bis{[(E)-3-(3,4-dihydroxyphenyl)prop-2-enoyl]oxy}-4,5-dihydroxycyclohexane-1-carboxylic acid monohydrate), CHO·HO, has been solved and refined using synchrotron powder X-ray diffraction data, and optimized using density functional techniques. Despite being purchased as anhydrous, cynarine crystallizes as a monohydrate and the crystal structure is characterized by alternating layers of hydrocarbon and hydrogen-bonding interactions parallel to the bc plane. Hydrogen bonds are significant in the crystal structure. The carboxylic acid group forms a strong intermolecular hydrogen bond to a hydroxy group of the quinic acid ring. Most of the hydroxy groups act as donors in O-H...O hydrogen bonding to carbonyl O atoms. One hydroxy group participates in bifurcated hydrogen bonds, one to a hydroxy group on the quinic acid ring and the other, an intramolecular interaction, to another hydroxy group. The powder pattern has been submitted to the International Centre for Diffraction Data (ICDD) for inclusion in the Powder Diffraction File (PDF-4).
Topics: Cinnamates; Crystallography, X-Ray; Hydrogen Bonding; Powder Diffraction; Powders; Synchrotrons; X-Ray Diffraction
PubMed: 35119388
DOI: 10.1107/S2053229622000687 -
Molecules (Basel, Switzerland) Aug 2021The solvatomorphism of the anthelmintic drug moxidectin is investigated, and a new solvatomorph with nitromethane is reported. Moreover, the hitherto unknown crystal...
The solvatomorphism of the anthelmintic drug moxidectin is investigated, and a new solvatomorph with nitromethane is reported. Moreover, the hitherto unknown crystal structures of the solvatomorphs with ethanol and 2-propanol are reported and discussed. The thermal characterization of these solvatomorphs through variable-temperature powder X-ray diffraction analysis (VT-PXRD) is also described, providing new insights into the crystallochemistry of this active pharmaceutical ingredient.
Topics: Crystallography, X-Ray; Hydrogen Bonding; Macrolides; Molecular Conformation; Powder Diffraction; Solvents; Temperature
PubMed: 34443452
DOI: 10.3390/molecules26164869 -
Philosophical Transactions. Series A,... Dec 2004The bulk properties of organic crystalline materials depend on their molecular and crystal structures but, as many of these materials cannot be prepared in a suitable... (Review)
Review
The bulk properties of organic crystalline materials depend on their molecular and crystal structures but, as many of these materials cannot be prepared in a suitable form for conventional single-crystal diffraction studies, structural characterization and rationalization of these properties must be obtained from powder diffraction data. The recent development of direct-space structure solution methods has enabled the study of a wide range of organic materials using powder diffraction data, many of structural complexity only made tractable by these advances in methodology. These direct-space methods are based on a number of global optimization techniques including Monte Carlo, simulated annealing, genetic algorithm and differential evolution approaches. In this article, the implementation and relative efficiency and reliability of these methods are discussed, and their impact on the structural study of organic materials is illustrated by examples of polymorphic systems, pharmaceutical, pigment and polypeptide structures and compounds used in the study of intermolecular networks.
Topics: Algorithms; Biopolymers; Crystallization; Molecular Conformation; Organic Chemicals; Powder Diffraction; X-Ray Diffraction
PubMed: 15539365
DOI: 10.1098/rsta.2004.1457 -
The Review of Scientific Instruments Nov 2022LISA [Linea Italiana per la Spettroscopia di Assorbimento X, Italian beamline for X-ray Absorption Spectroscopy (XAS)] is the Italian CRG (Collaborating Research Group)...
LISA [Linea Italiana per la Spettroscopia di Assorbimento X, Italian beamline for X-ray Absorption Spectroscopy (XAS)] is the Italian CRG (Collaborating Research Group) beamline at the ESRF (European Synchrotron Radiation Facility) dedicated to XAS [d'Acapito et al., J. Synchrotron Radiat. 26, 551-558 (2019)]. In this work, a methodical test of the LISA beamline in performing diffraction measurements is carried out. Synchrotron x-ray diffraction measurements would complement absorption spectroscopy techniques with the long-range characterization of the material under investigation, while XAS provides the short-range element selective information.
Topics: Synchrotrons; X-Ray Diffraction; Powders; Powder Diffraction; X-Rays
PubMed: 36461554
DOI: 10.1063/5.0107024 -
Acta Crystallographica. Section A,... May 2021Advances in instrumentation, as well as the development of powerful crystallographic software have significantly facilitated the collection of high-resolution...
Advances in instrumentation, as well as the development of powerful crystallographic software have significantly facilitated the collection of high-resolution diffraction data and have made X-ray powder diffraction (XRPD) particularly useful for the extraction of structural information; this is true even for complex molecules, especially when combined with synchrotron radiation. In this study, in-line with past instrumental profile studies, an improved data collection strategy exploiting the MYTHEN II detector system together with significant beam focusing and tailored data collection options was introduced and optimized for protein samples at the Material Science beamline at the Swiss Light Source. Polycrystalline precipitates of octreotide, a somatostatin analog of particular pharmaceutical interest, were examined with this novel approach. XRPD experiments resulted in high angular and d-spacing (1.87 Å) resolution data, from which electron-density maps of enhanced quality were extracted, revealing the molecule's structural properties. Since microcrystalline precipitates represent a viable alternative for administration of therapeutic macromolecules, XRPD has been acknowledged as the most applicable tool for examining a wide spectrum of physicochemical properties of such materials and performing studies ranging from phase identification to complete structural characterization.
Topics: Crystallography, X-Ray; Macromolecular Substances; Octreotide; Photons; Powder Diffraction
PubMed: 33944797
DOI: 10.1107/S2053273321001698 -
Advances in Protein Chemistry 2006A conformational change from the alpha-helical, cellular form of prion to the beta-sheet, scrapie (infectious) form is the central event for prion replication. The... (Review)
Review
A conformational change from the alpha-helical, cellular form of prion to the beta-sheet, scrapie (infectious) form is the central event for prion replication. The folding mechanism underlying this conformational change has not yet been deciphered. Here, we review prion pathology and summarize X-ray fiber and powder diffraction studies on the N-terminal fragments of prion protein and on short sequences that initiate the beta-assembly for various fibrils, including poly(L-alanine) and poly(L-glutamine). We discuss how the quarter-staggered beta-sheet assembly (like in polyalanine) and polar-zipper beta-sheet formation (like in polyglutamine) may be involved in the formation of the scrapie form of prion.
Topics: Powder Diffraction; Prions; Protein Conformation; X-Ray Diffraction
PubMed: 17190614
DOI: 10.1016/S0065-3233(06)73006-6 -
Journal of Pharmaceutical Sciences Nov 2020Florfenicol is an antimicrobial drug used in veterinary medicine and aquaculture. Two polymorphic forms called A and B have been reported in literature, but the relation...
Florfenicol is an antimicrobial drug used in veterinary medicine and aquaculture. Two polymorphic forms called A and B have been reported in literature, but the relation between these two forms are unknown. In order to get a better understanding of the behavior of solid florfenicol and the possible evolution from a metastable form to a stable one, an accurate thermodynamic study has been carried out by calorimetric measurements. For this purpose, temperatures and enthalpies of transition and of fusion of the stable and metastable forms have been measured by DSC. TGA has been used in view to detect the eventual existence of solvates which does not occur. In view to confirm the kind of transition, c measurements of the two forms have been performed with a C80 calorimeter. With these c values, it has been possible to determine the function of the variation of enthalpies as a function of temperature, ΔH = f (T). A study of the kinetic of transformation has been realized and is presented as well as the patterns of the X-ray powder diffraction from 295 to 426 K. This last approach confirms the crystal structure of form A of florfenicol previously reported in literature.
Topics: Calorimetry, Differential Scanning; Powder Diffraction; Thermodynamics; Thiamphenicol; X-Ray Diffraction
PubMed: 32721472
DOI: 10.1016/j.xphs.2020.07.017