A thorough characterization of the polysaccharide part of Mannoprotein Pools (MPs) from nine different yeast strains was performed to assess biosynthesis-pathways impact on mannoproteins macromolecular structure and l...
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A thorough characterization of the polysaccharide part of Mannoprotein Pools (MPs) from nine different yeast strains was performed to assess biosynthesis-pathways impact on mannoproteins macromolecular structure and later establish structure-function relationships regarding stabilization properties. The strains comprised one wildtype S. cerevisiae strain, its mutants Delta Mnn2 and Delta Mnn4 (non-ramified N-glycosylated backbone and lacking mannosyl-phosphorylation, respectively), enological Saccharomyces cerevisiae strains grown in different metabolic conditions (aerobic and anaerobic), and three non-Saccharomyces species: Hanseniaspora vineae, Torulaspora delbrueckii, and Schizosaccharomyces japonicus. Neutral sugars composition for MPs of all strains had mainly mannose but Schizosaccharomyces japonicus strain also presented approximately 33 % of galactose. MPs from non-Saccharomyces strains exhibited significant differences in glycosyl-linkage analysis, especially those from Torulaspora delbrueckii and S. japonicus strains. Global net charge analysis of MP from S. japonicus strain suggests the presence of unknown negatively charged ions. These results dismiss the general N-glycosylated and OMannosylated structures obtained from S. cerevisiae. HPSEC-MALLS-QELS-Viscometry analysis revealed higher intrinsic viscosity profiles ([eta]xMw) of H. vineae and S. japonicus MPs than S. cerevisiae ones. Metabolic conditions also influenced S. cerevisiae MPs biosynthesis: aerobiosis produced more negatively charged (-20C.g-1, net charge at pH 3.5) and less compact (rho = 2.8) MPs than anaerobiosis (-5C.g-1 and 1.4).
Linear-scaling electronic structure calculations of solvated biomolecules have been carried out using a semiempirical Hamiltonian and a new smooth solvation potential. These methods afford a new way of generating macr...
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Linear-scaling electronic structure calculations of solvated biomolecules have been carried out using a semiempirical Hamiltonian and a new smooth solvation potential. These methods afford a new way of generating macromolecular properties that include quantum electronic structure. In addition to the widely used classical electrostatic potential maps based on empirically derived static point charges, now fully quantum mechanical electrostatic potentials that include electronic polarization are possible. Linear-scaling electronic structure methods provide a host of response properties of the electron density such as Linear response functions, local hardness functions, and Fukui functions. It is the hope that these indices will extend insight into problems of biological macromolecular characterization. (C) 2000 John Wiley & Sons, Inc.
Investigations based on static and dynamic light-scattering studies were conducted to assess the influence of amylose content (0.0-65.8%) and microwave dispersion treatment (MDT) on the macromolecular features of star...
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Investigations based on static and dynamic light-scattering studies were conducted to assess the influence of amylose content (0.0-65.8%) and microwave dispersion treatment (MDT) on the macromolecular features of starches, including fractal behaviour. Values for apparent average molar mass ((M) over bar(w)), gyration radius ((R) over bar(G)) and hydrodynamic radius ((R) over bar(H)) were obtained using common extrapolation procedures to the zero scattering vector. The general trend showed a decrease in these values when amylose level or the intensity of MDT was increased. However, unexpected results were obtained. mainly for the starch with the highest amylose content and for long MDT times. The high q (R) over bar(G)-range [where q is the scattering vector;q = (4 pi n/lambda)sin(theta/2)] allowed the internal behaviour of starch samples to be studied as well. Kratky plots, fractal dimensions, and relaxation rate dependence on q revealed significant differences in internal structures and the influence of amylose content. At low amylose contents (0.0-28.5%), light-scattering behaviour was dominated by the amylopectin contribution, in agreement with Galinski and Burchard (Macromolecules 1995;28:2363), whereas at high amylose contents (52.5-65.8%), light-scattering behaviour was influenced by amylose despite the high dimensions of amylopectin. (C) 1999 Elsevier Science Ltd. All rights reserved.
Analytical ultracentrifugation is a classical method of biochemistry and molecular biology. Because it is a primary technique, sedimentation can provide first-principle hydrodynamic and first-principle thermodynamic i...
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Analytical ultracentrifugation is a classical method of biochemistry and molecular biology. Because it is a primary technique, sedimentation can provide first-principle hydrodynamic and first-principle thermodynamic information for nearly any molecule, in a wide range of solvents and over a wide range of solute concentrations. For many questions, it is the technique of choice. This review stresses what information is available from analytical ultracentrifugation and how that information is being extracted and used in contemporary applications.
Three commercial chitosans varying in average degree of acetylation (DA) were characterized in terms of average molar masses M-n, M-w, the second virial coefficient B and radius of gyration R-g,R-z, and intrinsic visc...
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Three commercial chitosans varying in average degree of acetylation (DA) were characterized in terms of average molar masses M-n, M-w, the second virial coefficient B and radius of gyration R-g,R-z, and intrinsic viscosities by membrane osmometry, static light scattering, and capillary viscometry in acetate buffer of pH 4.5. To obtain satisfactory light scattering data, the method used for clarification was of great importance. Combined ultracentrifugation and membrane filtration was found to be the method of choice. Using the model for wormlike chains with excluded volume and a logarithmic molar mass distribution, the persistence length L-p was determined as L-p = 6 nm. No concentration-dependent association was observed for the low concentrations studied. Samples were also fractionated on Sepharose CL-2B for subsequent light scattering and viscosity measurements to establish relationships between M-w and [eta] and R-g, respectively. These relationships were found to be independent of the DA for the bulk of molecularly dispersed chitosan. Model calculations aimed at checking the consistency of data led, as to be expected, to an increasing excluded volume effect with increasing molar mass and steadily increasing polydispersities of the fractions with increasing elution volume. The levelling off of the [eta]-M-w and R-g-M-w relations for fractions of increasingly high molar mass was assigned to chemical heterogeneity of samples in terms of DA distributions. (C) 1998 Elsevier Science Ltd. All rights reserved.
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