SMALL-ANGLE NEUTRON SCATTERING AND BIOMOLECULES (original) (raw)
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Ultra-small-angle neutron scattering: a new tool for materials research
Current Opinion in Solid State and Materials Science, 2004
Ultra-small-angle neutron scattering is a powerful new tool to quantitatively characterize the morphology of materials on length scales from 0.1 to 50 lm. The technique has already been used on a wide range of materials from hydrogels to geologic specimens. The data reveal a surprising richness of previously undetected morphological features. (D.W. Schaefer), magama-lian@sns.gov (M.M. Agamalian).
Protein structure and interactions in the solid state studied by small-angle neutron scattering
Faraday Discussions, 2012
Small-angle neutron scattering (SANS) is uniquely qualified to study the structure of proteins in liquid and solid phases that are relevant to food science and biotechnological applications. We have used SANS to study a model protein, lysozyme, in both the liquid and water ice phases to determine its gross-structure, interparticle interactions and other properties. These properties have been examined under a variety of solution conditions before, during, and after freezing. Results for lysozyme at concentrations of 50 mg mL À1 and 100 mg mL À1 , with NaCl concentrations of 0.4 M and 0 M, respectively, both in the liquid and frozen states, are presented and implications for food science are discussed.
Neutron small-angle scattering of biological macromolecules in solution
Journal of Applied Crystallography, 1974
In order to get an idea of the possible neutron small-angle scattering experiments with solutions of macromolecules at the high-flux reactor of the Institut Max von Laue-Paul Langevin at Grenoble, aqueous solutions of molecules with molecular weights from about one hundred to several millions have been studied. Changing the contrast by using different HzO/D20 mixtures the basic scattering functions could be determined. Zero-angle scattering from neutron and X-ray small-angle scattering experiments are compared. In the case of ferritin the molecular-weight distribution could be determined from the dependence of zero-angle scattering on the solvent. A considerable variation of the square of the radius of gyration R at low contrast ~ was observed. R 2 turned out to be a linear function of 1/~. The slope of the straight line is a measure of the homogeneity of the internal structure. Proton-deuteron exchange reactions have been studied. A time resolution of less than two seconds had been reached with myoglobin and other globular proteins.
Polymer Journal, 2011
Recent developments in small-angle neutron scattering (SANS) investigations on polymer gels are reviewed by encompassing (i) volume phase transition and microphase separation, (ii) inhomogeneities in polymer gels, (iii) pressure dependence of hydrophobic interaction and (iv) structural characterization of super-tough gels. These developments owe much to the understanding of gel inhomogeneities and advances in the precision analyses of SANS, such as the contrast variation method coupled with singular value decomposition and the accurate evaluation of incoherent scattering intensity. As one of the fruitful outcomes, deformation mechanisms in various types of super-tough gels are elucidated.
Small-angle neutron scattering from typical synthetic and biopolymer solutions
Colloid and Polymer Science, 2008
Small-angle neutron scattering (SANS) has been used to investigate the solution properties of four model polymers, two poly-amino acids [poly(lysine) and poly (proline)], and two water-soluble synthetic polymers [poly (acrylic acid) and poly(ethylene oxide)]. In each case, one of the two polymers is charged, while the other is neutral. SANS measurements were made in the semi-dilute concentration regime in two different solvents [d-water and dethylene glycol]. The scattering signals were decomposed into low-Q clustering and high-Q solvation contributions. The temperature dependence of the scattering parameters was determined for poly(lysine) and poly(ethylene oxide) solutions over the temperature range of 13 to 82°C. Analysis of the SANS spectra revealed that with increasing temperature, the solvation intensity increased in both solvents, while the clustering intensity increased in d-water and decreased in d-ethylene glycol. Significant differences were observed between the SANS spectra of charged and neutral polymer solutions. However, biopolymers and synthetic polymers exhibited qualitatively similar behavior.
Study of nanoscale structures in hydrated biomaterials using small-angle neutron scattering
Acta Biomaterialia, 2012
Distribution of water in three classes of biomedically relevant and degradable polymers was investigated using small-angle neutron scattering. In semicrystalline polymers, such as poly(lactic acid) and poly(glycolic acid), water was found to diffuse preferentially into the noncrystalline regions. In amorphous polymers, such as poly(D,L-lactic acid) and poly(lactic-co-glycolic acid), the scattering after 7-days of incubation was attributed to water in microvoids that form following the hydrolytic degradation of the polymer. In amorphous copolymers containing hydrophobic segments (desaminotyrosyl-tyrosine ethyl ester) and hydrophilic blocks (poly(ethylene glycol) PEG), a sequence of distinct regimes of hydration were observed: homogeneous distribution (~ 10 Å length scales) at <13 wt% PEG (~ 1 water per EG), clusters of hydrated domains (~50 Å radius) separated at 24 wt% PEG (1 to 2 water per EG), uniformly distributed hydrated domains at 41 wt % PEG (~ 4 water per EG), and phase inversion at > 50 wt% PEG (> 6 water per EG). Increasing PEG content increased the number of these domains with only a small decrease in distance between the domains. These discrete domains appeared to coalesce to form submicron droplets at 60 °C, above the melting temperature of crystalline PEG. Significance of such observations on the evolution of μm size channels that form during hydrolytic erosion is discussed.
Investigating Structure and Dynamics of Proteins in Amorphous Phases Using Neutron Scattering
Computational and structural biotechnology journal, 2017
In order to increase shelf life and minimize aggregation during storage, many biotherapeutic drugs are formulated and stored as either frozen solutions or lyophilized powders. However, characterizing amorphous solids can be challenging with the commonly available set of biophysical measurements used for proteins in liquid solutions. Therefore, some questions remain regarding the structure of the active pharmaceutical ingredient during freezing and drying of the drug product and the molecular role of excipients. Neutron scattering is a powerful technique to study structure and dynamics of a variety of systems in both solid and liquid phases. Moreover, neutron scattering experiments can generally be correlated with theory and molecular simulations to analyze experimental data. In this article, we focus on the use of neutron techniques to address problems of biotechnological interest. We describe the use of small-angle neutron scattering to study the solution structure of biological mo...
Small-Angle Neutron Scattering by a Strongly Denatured Protein Analysis Using Random Polymer Theory
Small-angle neutron scattering profiles are presented from phosphoglycerate kinase, in the native form and strongly denatured in 4 M guanidinium chloride (GdnHCI) solution. The data are interpreted using a model in which the excess scattering density associated with the protein is represented as a finite freely jointed chain of spheres. The similarity of the model-derived scattering function to experiment increases asymptotically with the number of spheres. The improvement of the fit obtained with more than -200 spheres (i.e., two residues per sphere) is insignificant. The effects of finite size of the scattering units and of scattering length variation along the polypeptide chain are examined. Improved agreement with experiment is obtained when these effects are taken into account. A method for rapid calculation of the scattering profile of a full, all-atom configuration is examined. It is found that a representation of the chain containing two scattering units per residue, placed at the backbone and side-chain scattering length centroids, reproduces the full, all-atom profile to within 2%.