Immunostimulatory Polysaccharides fromChlorellapyrenoidosa. A New Galactofuranan. Measurement of Molecular Weight and Molecular Weight Dispersion by DOSY NMR

2006 ◽  
Vol 7 (8) ◽  
pp. 2368-2376 ◽  
Author(s):  
Erick Reyes Suárez ◽  
Raymond Syvitski ◽  
Jaroslav A. Kralovec ◽  
Miguel D. Noseda ◽  
Colin J. Barrow ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Dosy Nmr

1H DOSY NMR Determination of the Molecular Weight and the Solution Properties of Poly(N-acryloylmorpholine) in Various Solvents

2016 ◽  
Vol 217 (20) ◽  
pp. 2286-2293 ◽  
Author(s):  
Cécile Chamignon ◽  
Damien Duret ◽  
Marie-Thérèse Charreyre ◽  
Arnaud Favier
Keyword(s):  
Molecular Weight ◽  
Solution Properties ◽  
Dosy Nmr

scholarly journals Application of 1H DOSY NMR in Measurement of Polystyrene Molecular Weights

2020 ◽  
Vol 36 (2) ◽  
Author(s):  
Nguyen Hoai Nam ◽  
Nguyen Huu Tho ◽  
Nguyen Minh Ngoc ◽  
Pham Quang Trung
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Hydrodynamic Radius ◽  
Gel Permeation Chromatography ◽  
Resonance Spectroscopy ◽  
Solvent Interaction ◽  
Molecular Weights ◽  
External Calibration Curve ◽  
Dosy Nmr

In this work, we studied the applicability of diffusion ordered nuclear magnetic resonance spectroscopy (DOSY NMR) as an alternative method in determination of polystyrene molecular weight. DOSY NMR spectroscopy allows measuring the diffusion coefficient of molecule which directly depend on hydrodynamic radius and so on, average molar mass in weight (Mw). By using commercial polystyrene (PS) standards, an external calibration curve was established. Based on the excellent linear correlation between diffusion coefficient (logD) and molecular weight (logM), the molecular weight of polystyrene can be predicted using the following equation . The validation was done by comparing with the Mw value obtained by gel permeation chromatography within less than 5% deviation. From the diffusion coefficient, some property of polystyrene in solution, such as Flory coefficient and polymer-solvent interaction, were also studied. The Flory coefficient confirmed that chloroform is a good solvent for PS.

scholarly journals Accurate molecular weight determination of small molecules via DOSY-NMR by using external calibration curves with normalized diffusion coefficients

2015 ◽  
Vol 6 (6) ◽  
pp. 3354-3364 ◽  
Author(s):  
Roman Neufeld ◽  
Dietmar Stalke
Keyword(s):  
Molecular Weight ◽  
Small Molecules ◽  
Calibration Curve ◽  
Diffusion Coefficients ◽  
Molecular Weight Determination ◽  
External Calibration ◽  
Calibration Curves ◽  
External Calibration Curve ◽  
Dosy Nmr

We describe a novel development of MW-determination by using an external calibration curve approach with normalized diffusion coefficients.

Evaluation of the dark field method for large association of spread DNA

1978 ◽  
Vol 36 (2) ◽  
pp. 190-191
Author(s):  
Douglas C. Barker
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Mitochondrial Dna ◽  
Extraction Method ◽  
Field Method ◽  
Dark Field ◽  
Kinetoplast Dna ◽  
Field Electron ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A number of satisfactory methods are available for the electron microscopy of nicleic acids. These methods concentrated on fragments of nuclear, viral and mitochondrial DNA less than 50 megadaltons, on denaturation and heteroduplex mapping (Davies et al 1971) or on the interaction between proteins and DNA (Brack and Delain 1975). Less attention has been paid to the experimental criteria necessary for spreading and visualisation by dark field electron microscopy of large intact issociations of DNA. This communication will report on those criteria in relation to the ultrastructure of the (approx. 1 x 10-14g) DNA component of the kinetoplast from Trypanosomes. An extraction method has been developed to eliminate native endonucleases and nuclear contamination and to isolate the kinetoplast DNA (KDNA) as a compact network of high molecular weight. In collaboration with Dr. Ch. Brack (Basel [nstitute of Immunology), we studied the conditions necessary to prepare this KDNA Tor dark field electron microscopy using the microdrop spreading technique.

Introduction

1978 ◽  
Vol 36 (3) ◽  
pp. 543-544
Author(s):  
W. Bernard
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Nucleic Acid ◽  
Gene Mapping ◽  
Molecular Genetics ◽  
Cell Biology ◽  
Gene Activity ◽  
Close Connection ◽  
Basic Information ◽  
Simple Systems

In comparison to many other fields of ultrastructural research in Cell Biology, the successful exploration of genes and gene activity with the electron microscope in higher organisms is a late conquest. Nucleic acid molecules of Prokaryotes could be successfully visualized already since the early sixties, thanks to the Kleinschmidt spreading technique - and much basic information was obtained concerning the shape, length, molecular weight of viral, mitochondrial and chloroplast nucleic acid. Later, additonal methods revealed denaturation profiles, distinction between single and double strandedness and the use of heteroduplexes-led to gene mapping of relatively simple systems carried out in close connection with other methods of molecular genetics.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

Conformation of eukaryotic ribosomal RNAs

1983 ◽  
Vol 41 ◽  
pp. 592-593
Author(s):  
M. Boublik ◽  
G. Thornton ◽  
G. Oostergetel ◽  
J.F. Hainfeld ◽  
J.S. Wall
Keyword(s):  
Molecular Weight ◽  
Mass Measurement ◽  
Carbon Film ◽  
Structural Complexity ◽  
Scanning Transmission Electron Microscope ◽  
Electron Microscopic ◽  
Pure Nitrogen ◽  
Freeze Dried ◽  
Scanning Transmission ◽  
Partially Unfolded

Understanding the structural complexity of ribosomes and their role in protein synthesis requires knowledge of the conformation of their components - rRNAs and proteins. Application of dedicated scanning transmission electron microscope (STEM), electrical discharge of the support carbon film in an atmosphere of pure nitrogen, and determination of the molecular weight of individual rRNAs enabled us to obtain high resolution electron microscopic images of unstained freeze-dried rRNA molecules from BHK cells in a form suitable for evaluation of their 3-D structure. Preliminary values for the molecular weight of 28S RNA from the large and 18S RNA from the small ribosomal subunits as obtained by mass measurement were 1.84 x 106 and 0.97 x 106, respectively. Conformation of rRNAs consists, in general, of alternating segments of intramolecular hairpin stems and single stranded loops in a proportion which depends on their ionic environment, the Mg++ concentration in particular. Molecules of 28S RNA (Fig. 1) and 18S RNA (not shown) obtained by freeze-drying from a solution of 60 mM NH+4 acetate and 2 mM Mg++ acetate, pH 7, appear as partially unfolded coils with compact cores suggesting a high degree of ordered secondary structure.

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