Galactosamine Polymer Isolated from the Cell Wall of Neisseria sicca

1972 ◽  
Vol 50 (4) ◽  
pp. 345-351 ◽  
Author(s):  
G. A. Adams ◽  
A. S. Chaudhari
Keyword(s):  
Cell Wall ◽  
Optical Rotation ◽  
Gel Permeation Chromatography ◽  
Molar Ratio ◽  
Branch Points ◽  
Weight Estimation ◽  
Glycosidic Bonds ◽  
A Value ◽  
Neisseria Sicca ◽  
End Group

A D-galactosamine polymer having a molar ratio of galactosamine–acetyl–phosphorus (1.0:1.0:0.35) has been isolated from the cell wall of Neisseria sicca. Its homogeneity was established by free-boundary electrophoresis, ultracentrifugal sedimentation, and gel permeation chromatography. Molecular weight estimation by reducing end group assay gave a value of [Formula: see text] 18 500. Methylation analysis indicated that the main glycosidic linkages were (1 → 4) and (1 → 6) with a minimum of 10% branch points. The glycosidic bonds were indicated as being in the α configuration by the high positive optical rotation of the polysaccharide and also from infrared spectrum evidence. Both the acetyl and phosphate contents were relatively unchanged by the Hakamori methylation procedure. Although galactosamine polymers have been found in a number of fungi, the present instance appears to be the first report of their presence in bacteria.

THE CONSTITUTION OF A POLYURONIDE HEMICELLULOSE FROM WHEAT STRAW

1952 ◽  
Vol 30 (9) ◽  
pp. 698-710 ◽  
Author(s):  
G. A. Adams
Keyword(s):  
Wheat Straw ◽  
Uronic Acid ◽  
Glucuronic Acid ◽  
Periodate Oxidation ◽  
Reducing Power ◽  
Molar Ratio ◽  
Acid Complex ◽  
Glycosidic Bonds ◽  
A Chain ◽  
End Group

The structure of a polyuronide hemicellulose from wheat straw containing xylose, arabinose, and hexuronic acid units has been investigated. Graded hydrolysis preferentially removed anhydro-L-arabinose units leaving a xylan to which uronic acid units were attached. Methylation and hydrolysis yielded 2,3,4-trimetliyl xylose (2.7%) indicating one nonreducing end group per 37 units; 2,3,5-trimethyl-L-arabinose, 2,3-dimethyl-D-xylose, and 2-methyl-D-xylose were found in a molar ratio 1:5:1. In addition, a methylated uronic acid complex was recovered which on extensive hydrolysis yielded an aldobiuronic acid. The latter, on reduction with sodium borohydride, yielded 2,3,4-trimethyl glucose (1 mole) and 2-methyl xylose (1 mole); the structure 2-methyl 3[2,3,4-trimethyl α-D-glucuronosido] D-xylose was therefore indicated for the methylated aldobiuronic acid.A structure for the hemicellulose is proposed which consists of approximately 32 anhydro-D-xylose units linked β 1,4- in a chain to which five anhydro-L-arabinose and three D-glucuronic acid units are attached as side groups by 1,3-glycosidic bonds. Results of periodate oxidation and estimation of reducing power support the proposed structure.

Digestible cell wall and undigested cellular contents of two grasses of low net energy value for growing cattle

1982 ◽  
Vol 99 (1) ◽  
pp. 207-208 ◽  
Author(s):  
K. W. Moir
Keyword(s):  
Cell Wall ◽  
Organic Matter ◽  
Dry Matter ◽  
Total Cell ◽  
Net Energy ◽  
Previous Evidence ◽  
Energy Value ◽  
A Value ◽  
Net Energy Value ◽  
Range Of Values

SUMMARYIn two grasses of low net energy value for growth and fattening of cattle, digestible cell-wall values were close to 40% of forage organic matter (OM), similar to the expected value for grass. A value of 14% of forage OM for apparently undigested cellular contents in both grasses was just outside the range of values for grass. The data supported previous evidence that total cell wall is the only value that can be used at present to define grass in terms of its digestible dry matter.

scholarly journals Microbubbles Decorated with Dendronized Magnetic Nanoparticles for Biomedical Imaging. Effective Stabilization via Fluorous Interactions

2019 ◽  
Author(s):  
Da Shi ◽  
Justine Wallyn ◽  
Dinh-Vu Nguyen ◽  
Francis Perton ◽  
Delphine Felder-Flesch ◽  
...  
Keyword(s):  
Molar Ratio ◽  
Aqueous Dispersions ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Investigation ◽  
End Groups ◽  
Mixed Films ◽  
Effective Stabilization ◽  
Effective Result ◽  
End Group

Dendrons fitted with three oligoethylene glycol (OEG) chains, one of which carrying a fluorinated or hydrogenated end group, and bearing a bisphosphonate polar head (C n X2 n +1OEG8Den, X = F or H; n= 2 or 4) were synthesized and grafted on the surface of iron oxide nanoparticles (IONPs) for microbubble-mediated imaging and therapeutic purposes. The size and stability of the dendronized IONPs (IONP@C n X2 n +1OEG8Den) in aqueous dispersions were monitored by dynamic light scattering. Investigation of the spontaneous adsorption of IONP@C n X2 n +1OEG8Den at the interface between air - or air saturated with perfluorohexane - and an aqueous phase establishes that exposure to the fluorocarbon gas markedly increases the rate of adsorption of the dendronized IONPs to the gas/water interface and decreases the equilibrium interfacial tension. This suggests that fluorous interactions are at play between the supernatant fluorocarbon gas and the fluorinated end groups of the dendrons. Furthermore, small, stable perfluorohexane-stabilized microbubbles (MBs) with a dipalmitoylphosphatidylcholine (DPPC) shell that incorporates IONP@C n X2 n +1OEG8Den (DPPC/Fe molar ratio 28:1) were prepared and characterized using both optical microscopy and an acoustical method of size determination. The dendrons fitted with fluorinated end groups lead to smaller and more stable MBs than those fitted with hydrogenated groups. The most effective result is already obtained with C2F5, for which MBs, ~1.0mm in radius, reach a half-life of ~6.0 h. An atomic force microscopy investigation of spin-coated mixed films of DPPC/IONP@C2X5OEG8Den combinations (molar ratio 28:1) shows that the IONPs grafted with the fluorinated dendrons are located within the phospholipid film, while those grafted with the hydrocarbon dendrons are completely absent from the phospholipid film.

Study on Synthesis of Cyclotriphosphazene Containing Aminopropylsilicone Functional Group as Flame Retardant

2013 ◽  
Vol 683 ◽  
pp. 25-29 ◽  
Author(s):  
Lan Lan He ◽  
Yi Zhang ◽  
Zhao Lu Qin ◽  
Yan Hua Lan ◽  
Ding Hua Li ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Chemical Structure ◽  
Gel Permeation Chromatography ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Element Analysis ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Industrial Grade ◽  
Distribution Calculation ◽  
Optimum Reaction

A novel non-halogen flame retardant APESP, cyclotriphosphazene containing six aminopropyltriethoxysilicone functional groups N3P3[NH(CH2)3Si(OCH2CH3)3]6, was synthesized by menas of SN2 nucleophilic substitution reaction, using hexachlorocyclotriphosphazene(HCCP) and 3-aminopropyltriethoxy-silane (KH550) as material. Firstly the industrial grade HCCP was purified through recrystallization and sublimation. Then the reaction process was investigated to prompt the yield, and the optimum reaction conditions were as follows: triethylamine as acid-binding agent, tetrahydrofuran as solvent, HCCP/KH550/triethylamine molar ratio 1:7.2:7.2, dripping time: 1 hour, temperature: 67°C and reaction time: 20h. Maximum APESP yield reached 94.3%. The chemical structure and purity was characterized by element analysis, Fourier-transformed infrared spectroscopy (FTIR), mass spectrum, gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) analysis. The results showed that the structure of synthesized product is consistent with the theoretical structure, in which the chlorine atoms were completely substituted. The charge distribution calculation of HCCP and KH550 confirmed the reaction mechanism.

scholarly journals Molar Ratio Effect of Sodium to Chloride Ions on the Electrochemical Corrosion of Alloy 600 and SA508 in HCl + NaOH Mixtures

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1970
Author(s):  
Do Haeng Hur ◽  
Jeoh Han ◽  
Jun Choi
Keyword(s):  
Electrochemical Corrosion ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Molar Ratio ◽  
Alloy 600 ◽  
Galvanic Coupling ◽  
Ratio Effect ◽  
Molar Ratios ◽  
Corrosion Rates ◽  
A Value

This study aims to investigate the molar ratio effect of sodium to chloride ions on the corrosion of an Alloy 600 steam generator tube and an SA508 tubesheet material. The corrosion behavior was evaluated in solutions with three different molar ratios of sodium to chloride ions using a potentiodynamic polarization method. The corrosion potentials and corrosion rates of both the two materials were significantly decreased as the molar ratio increased from 0.1 to 10. Therefore, it is recommended that the molar ratio control to a value of 1 is beneficial only when the crevice chemistry has a low molar ratio with an acidic pH. The corrosion potentials and corrosion rates were little affected by the total sodium and chloride ion concentrations. SA508 acted as an anode and its corrosion rate was accelerated by galvanic coupling with Alloy 600.

scholarly journals Methylene-Bridged Tridentate Salicylaldiminato Binuclear Titanium Complexes as Copolymerization Catalysts for the Preparation of LLDPE through [Fe]/[Ti] Tandem Catalysis

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1114 ◽  
Author(s):  
Yani Luo ◽  
Jian Li ◽  
Derong Luo ◽  
Qingliang You ◽  
Zifeng Yang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Temperature ◽  
Gel Permeation Chromatography ◽  
13C Nmr Spectroscopy ◽  
Molar Ratio ◽  
Tandem Catalysis ◽  
Titanium Complexes ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Branching Degree

A novel tandem catalysis system consisted of salicylaldiminato binuclear/mononuclear titanium and 2,6-bis(imino)pyridyl iron complexes was developed to catalyze ethylene in-situ copolymerization. Linear low-density polyethylene (LLDPE) with varying molecular weight and branching degree was successfully prepared with ethylene as the sole monomer feed. The polymerization conditions, including the reaction temperature, the Fi/Ti molar ratio, and the structures of bi- or mononuclear Ti complexes were found to greatly influence the catalytic performances and the properties of obtained polymers. The polymers were characterized by differential scanning calorimetry (DSC), high temperature gel permeation chromatography (GPC) and high temperature 13C NMR spectroscopy, and found to contain ethyl, butyl, as well as some longer branches. The binuclear titanium complexes demonstrated excellent catalytic activity (up to 8.95 × 106 g/molTi·h·atm) and showed a strong positive comonomer effect when combined with the bisiminopyridyl Fe complex. The branching degree can be tuned from 2.53 to 22.89/1000C by changing the reaction conditions or using different copolymerization pre-catalysts. The melting points, crystallinity and molecular weights of the products can also be modified accordingly. The binuclear complex Ti2L1 with methylthio sidearm showed higher capability for comonomer incorporation and produced polymers with higher branching degree and much higher molecular weight compared with the mononuclear analogue.

Randomly Branched Polymers. II. Computer Analysis of Gel-Permeation Chromatograms

1976 ◽  
Vol 49 (5) ◽  
pp. 1290-1304
Author(s):  
M. Kurata ◽  
H. Okamoto ◽  
M. Iwama ◽  
M. Abe ◽  
T. Homma
Keyword(s):  
Molecular Weight ◽  
Weight Distribution ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Computer Method ◽  
Branched Polymers ◽  
Branch Points ◽  
Weight Average Molecular Weight ◽  
Degree Of Branching ◽  
Gel Permeation

Abstract An iterative computer method was proposed for estimating the degree of branching and molecular weight distribution simultaneously from a pair of measurements on intrinsic viscosity and gel-permeation chromatography. The validity of the method as applied to randomly branched polymers was tested by using both fractionated and unfractionated samples of branched polystyrenes. It was experimentally concluded that the average number of branch points per unit molecular weight, λ, can be determined by this method with an accuracy of about 15%, and the weight-average molecular weight with accuracy of about 10%.

Ethylene Polymerization by Thioether Bridged Dinuclear Titanocene Complex

2011 ◽  
Vol 213 ◽  
pp. 354-357 ◽  
Author(s):  
Yu Jing Nie ◽  
Ming Yang
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Ethylene Polymerization ◽  
Gel Permeation Chromatography ◽  
Molar Ratio ◽  
Polymerization Temperature ◽  
High Concentration ◽  
Highly Active ◽  
Cyclopentadienyl Ligand ◽  
Broad Molecular Weight Distribution

The thioether bridged metallocene complex [(C5H5)Cl2TiC5H4CH2CH2]2S has been synthesized by treating the dilithium salts of the thioether bridged cyclopentadienyl ligand with two equivalents of C5H5TiCl3 and characterized by 1HMNR and elemental analysis. After activation with methylaluminoxane (MAO), the complex was highly active catalysts for homogeneous ethylene polymerization in toluene. The influence of the molar ratio [MAO]/[Cat], the catalyst concentration, time and temperature have been studied systematically. The catalytic activity of 1 is 3.63×105 g PE/mol•Cat•h. Rising the polymerization temperature decreases the catalytic activity for 1. A high concentration of the catalysts drops the catalytic activity as well as the molecular weight of polyethylene for the complex. High temperature gel permeation chromatography (HT-GPC) proves the production of polyethylene with a broad molecular weight distribution (MWD).

scholarly journals Preliminary Characterization of a Homogeneous Polysaccharide with Anticomplement Activity from Sijunzi Decoction

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Ruijun Wang ◽  
Yunfei Ji ◽  
Ying Peng ◽  
Xiaobo Li
Keyword(s):  
Immune System ◽  
Size Exclusion ◽  
Molar Ratio ◽  
Classical Pathway ◽  
Glycosidic Bonds ◽  
Atomic Force ◽  
Exclusion Chromatography ◽  
Ft Ir ◽  
Immune System Regulation

Sijunzi decoction (SJZD) is a classical herbal prescription in traditional Chinese medicine (TCM) used for enhancing the function of immune system. In previous studies, a polysaccharide fraction S-3 was screened from SJZD by assessment of immune system regulation, intestinal microbiota, and SCFA in order to explore the immune active ingredients in SJZD. In the present study, S-3 was further purified, and a homogeneous polysaccharide S-3-1 with a molecular mass of 13.5 × 104 Da was obtained after further fractionation by Sephadex G-150 size-exclusion chromatography. The immunological activities of S-3-1 were assayed in vitro for the first time. The determination of the anticomplement activity showed that S-3-1 displayed inhibitory effects on classical pathway of the complement system, with CH50 values of 530 μg/mL. The FT-IR analysis showed that S-3-1 had absorptive peaks characteristic of polysaccharides. The methylation and GC-MS analysis showed that it is comprised of Rha, Ara, Xyl, Man, Gal, and Glc in a relative molar ratio of 0.35 : 0.37 : 1.4 : 0.31 : 3 : 0.8 and that it mainly contained 1,4-linked-Glc and 1,6-linked-Gal glycosidic bonds. The morphology of S-3-1 was observed by atomic force microscope (AFM). These results provided evidences for tracking the material basis of SJZD immune activity.

scholarly journals The configuration of 2,6-diamino-3-hydroxypimelic acid in microbial cell walls

1969 ◽  
Vol 115 (4) ◽  
pp. 797-805 ◽  
Author(s):  
H R Perkins
Keyword(s):  
Cell Wall ◽  
Hydroxy Group ◽  
Cell Walls ◽  
Optical Rotation ◽  
Periodate Oxidation ◽  
Ring Closure ◽  
Diaminopimelic Acid ◽  
Amino Group ◽  
Amino Groups ◽  
Peptide Linkage

β-Hydroxydiaminopimelic acid, together with some diaminopimelic acid, occurs in the cell-wall mucopeptide of certain Actinomycetales. These components were converted into their di-DNP derivatives and separated by chromatography. Hence the relative proportions present in the cell walls of a number of species were measured. The problem of acid-induced inversion of configuration was studied. Of the diaminohydroxypimelic acids isomer B (see Scheme 2; amino groups meso, hydroxy group threo to its neighbouring amino group) always predominated but a small proportion of isomer D (amino groups l, hydroxy group erythro) also occurred. The configuration of the diaminohydroxypimelic acids was determined by periodate oxidation to glutamic γ-semialdehyde, which underwent spontaneous ring-closure. Reduction with sodium borohydride produced optically active proline, the configuration of which was determined by direct measurement of the optical rotation of DNP-proline. Un-cross-linked diaminohydroxypimelic acid in the cell wall was oxidized with periodate in the presence of ammonia. Since the remaining amino group was bound in peptide linkage, ring-closure was prevented and borohydride reduction of the aldehyde–ammonia presumed to be present resulted in the formation of ornithine. The quantity of ornithine was used as a measure of the degree of cross-linking.

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