scholarly journals Molecular weight dependent antistaphylococcal activities of oligomers/polymers synthesized from 3-aminopyridine

2010 ◽  
Vol 75 (9) ◽  
pp. 1203-1208 ◽  
Author(s):  
Cahit Akgul ◽  
Mehmet Yildirim
Keyword(s):  
Molecular Weight ◽  
Antibacterial Activities ◽  
Maximum Activity ◽  
Size Exclusion ◽  
Polycondensation Reaction ◽  
Reaction Conditions ◽  
Molecular Weights ◽  
Antistaphylococcal Activity ◽  
Exclusion Chromatography ◽  
The Relationship

The main aim of this study was to investigate the relationship between molecular weight and the antistaphylococcal activity of oligomers/polymers synthesized from 3-aminopyridine. Different oligomers/polymers were synthesized from 3-aminopyridine by changing the oxidative polycondensation reaction conditions. They were characterized by size exclusion chromatography and their antibacterial activities were compared by employing standardized susceptibility assays. The obtained experimental results demonstrated that 3-aminopyridine had no antistaphylococcal activity. However, as a result of polymerization, strong antistaphylococcal activity was obtained. Oligomers/polymers synthesized from 3-aminopyridine had varying degrees of antistaphylococcal activity and the maximum activity was obtained from relatively very short oligomers. It was therefore concluded that polymerization of 3-aminopyridine is required for antistaphylococcal activity and strength of this activity depends on the molecular weights of the synthesized molecules.

Comparison of exopolysaccharides from mucoid and nonmucoid strains of Clavibacter michiganensis subspecies sepedonicus

1993 ◽  
Vol 39 (3) ◽  
pp. 291-296 ◽  
Author(s):  
Paul J. Henningson ◽  
Neil C. Gudmestad
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Size Exclusion ◽  
Enzyme Linked Immunosorbent Assay ◽  
Low Molecular Weight ◽  
Neutral Sugar ◽  
Clavibacter Michiganensis ◽  
Serological Reaction ◽  
Molecular Weights ◽  
Exclusion Chromatography

The exopolysaccharides produced by six strains of Clavibacter michiganensis ssp. sepedonicus were isolated and purified by liquid chromatography. Neutral sugar composition and molecular weights were determined for each polysaccharide fraction, using gas chromatography and high-performance size-exclusion chromatography. The serological reaction of each fraction was tested using enzyme-linked immunosorbent assay. Exopolysaccharide from nonmucoid strains contained only low molecular weight polysaccharides (1.5 × 103 to 1.1 × 104). Exopolysaccharide from mucoid and intermediate strains could be separated into low (4.0 × 103 to 1.1 × 104) molecular weight and high (5.0 × 105 to 1.6 × 106) molecular weight fractions. High molecular weight polysaccharides were composed almost exclusively of galactose, glucose, and fucose. The ratios of these sugars were highly variable among strains. Low molecular weight polysaccharides were primarily composed of galactose with significant and varying amounts of glucose, rhamnose, mannose, and ribose. All polysaccharide fractions except one, produced by a nonmucoid strain, reacted in the immunoassay test.Key words: exopolysaccharide, polysaccharide, Clavibacter, michiganensis, sepedonicus.

Relationships between Molecular Weights and Rheological Properties of Asphalts

1996 ◽  
Vol 1535 (1) ◽  
pp. 10-14 ◽  
Author(s):  
Jan F. B ranthaver ◽  
Raymond E. Robertson ◽  
John J. Duvall
Keyword(s):  
Molecular Weight ◽  
Rheological Properties ◽  
Size Exclusion Chromatography ◽  
Size Exclusion ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Molecular Associations ◽  
Weight Distributions ◽  
Exclusion Chromatography ◽  
Microstructural Model

It is known that the rheological properties of mixtures of organic compounds are functions of molecular weight distributions. However, with respect to asphalts, which are composed of many different compounds and compound types, molecular weights are difficult to measure. This difficulty occurs because the molecular associations that form are held together by forces of varying strengths and are partly broken up by heat and solvents. In theory, the strongest molecular associations in asphalts should have the greatest influence on the rheological properties of asphalts. These associations would be expected to be the major contributors to the asphalt's behaving as if it were a relatively high molecular weight material. Asphalt molecular associations should be isolatable by means of size exclusion chromatography. Several fractions of varying molecular weights (measured by membrane osmometry and vapor phase osmometry) were isolated from Strategic Highway Research Program (SHRP) asphalt AAD-1 by preparative size exclusion chromatography. Molecular weights of these fractions ranged from approximately 2,000 daltons to over 40,000 daltons. When these fractions were independently mixed with asphalt AAD-1 solvent moiety, mixtures were obtained whose rheological properties were a function of the molecular weights and concentrations of the associated materials. These results support the microstructural model of asphalt proposed during SHRP. The results also suggest that the unusual rheological properties of some asphalts may be explained by measuring molecular weight distributions. This type of information may be useful for modification of asphalts to achieve desirable rheological properties.

Characterization of polyamides 6, 11, and 12. Determination of molecular weight by size exclusion chromatography (IUPAC Technical Report)

2004 ◽  
Vol 76 (11) ◽  
pp. 2009-2025 ◽  
Author(s):  
E. C. Robert ◽  
Rudolf Bruessau ◽  
J.-E. Dubois ◽  
Bernard Jacques ◽  
Nico Meijerink ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
Working Party ◽  
Size Exclusion ◽  
Molecular Weights ◽  
Relative Standard ◽  
Exclusion Chromatography ◽  
Iupac Commission ◽  
Commercial Polymers

This report presents the results from IUPAC Working Party IV.2.2 of the global trial within the framework of IUPAC Commission IV.2, “Characterization of Commercial Polymers”. The results were compared on the basis of molecular weight obtained by size exclusion chromatography (SEC)using different techniques practiced in participating laboratories, the majority of which were materials suppliers. The practical methodologies used different solvents for the polymers, in particular, benzyl alcohol, 1,1,1,3,3,3 hexafluoropropan-2-ol and tetrahydrofuran; the latter solvent was used after chemical modification of the polyamides, in general with trifluoroacetic anhydride. Eight laboratories participated in the trial. The repeatability for molecular weight in each laboratory was good, whatever technique was used, the relative standard deviation averaged over all laboratories being around 3%. The deviations in distribution of molecular weights with different experimental methodologies were broader, but were reasonably good despite the diversity of methods. The differences in the distribution correspond to a confidence interval of about 30% in molecular weight.

Molecular Weight Characterization of Food Grade Polyethylenes and Extractables by Size Exclusion Chromatography

1981 ◽  
Vol 64 (4) ◽  
pp. 1008-1013
Author(s):  
Roger C Snyder ◽  
Charles V Breder
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
High Density ◽  
Size Exclusion ◽  
Low Density ◽  
Food Grade ◽  
Molecular Weights ◽  
Exclusion Chromatography ◽  
Band Spreading

Abstract Size exclusion chromatography (SEC) was used to characterize the molecular weight distribution (MWD) of 6 low density and 6 high density food grade polyethylene resins. The hexane and xylene extractable fractions of these 12 resins were also analyzed by SEC. An IBM 370/168 computer with an APL program was used to analyze the chromatograms and correct for chromatographic band spreading and skewing. Calculated weight average molecular weights (Mw) for the resins ranged from 40 000 to 200 000 and number average molecular weights (Mn) ranged from 6000 to 60 000. Median values of Mw and Mn were 1800 and 950, respectively, for hexane extractables from the low density resins, and were 310 and 290, respectively, for hexane extractables from the high density resins. Corresponding Mw and Mn values for xylene extractables were consistently larger than those for hexane extractables.

Application possibilities of preparative size exclusion chromatography to analytical problems in polymer science

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Hanneke M. L. Thijs ◽  
Michael A. R. Meier ◽  
Ulrich S. Schubert
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
Size Exclusion ◽  
Molecular Weight Determination ◽  
Polymer Science ◽  
Polymer Architecture ◽  
Molecular Weights ◽  
Star Shaped Polymer ◽  
Exclusion Chromatography ◽  
Good Agreement

AbstractThe application possibilities of preparative size exclusion chromatography for the detailed analysis of polymer analytes are discussed. Using the example of star-shaped polymer architecture, the possibilities of utilizing fractions obtained from preparative size exclusion chromatography and their subsequent off-line characterization with a variety of hyphenated analytic techniques are discussed and compared to one another. It was, for instance, possible to obtain an absolute SEC calibration for the investigated star-shaped polymers that showed very good agreement with theoretical expected values and values obtained by absolute molecular weight determination techniques by analyzing fractions of different molecular weights of this polymer architecture by MALDI-TOFMS in order obtain the Mp values required for SEC calibrations. Moreover, the star-shaped polymers were investigated by SEC-viscometry in order to obtain their absolute molecular weight. All analytical results are compared to each other and possibilities as well as limitations are discussed.

Enzymatic polymerization of sodium lignosulfonates: effect of catalysts, initial molecular weight, and mediators

2013 ◽  
Vol 91 (3) ◽  
pp. 220-225 ◽  
Author(s):  
Nidal Madad ◽  
Latifa Chebil ◽  
Celine Charbonnel ◽  
Irina Ioannou ◽  
Mohamed Ghoul
Keyword(s):  
Molecular Weight ◽  
Trametes Versicolor ◽  
Size Exclusion ◽  
Enzymatic Polymerization ◽  
Molecular Weights ◽  
Exclusion Chromatography ◽  
Phenolic Group ◽  
Ft Ir ◽  
Rhus Vernicifera ◽  
Substrate Concentrations

The aim of this study was to investigate the effect of different parameters on the enzymatic polymerization of sodium lignosulfonates (SLS) by laccase, compared with the chemical treatment by manganese III. Different initial molecular weights of SLS (commercial SLS (17 800 Da), F1 (4300 Da), F2 (2500 Da), and F3 (2300 Da)) were tested. Size exclusion chromatography (SEC-UV), Fourier transform infrared (FT-IR) and phenolic group determination showed that SLS molecular weight increases depending on the laccase origin, the enzyme, and the substrate concentrations and the initial molecular weight of the SLS fractions. The highest molecular weight (Mw) was obtained by fungal laccases, specifically when using laccase from Trametes versicolor, while no reactivity was observed by plant laccase (laccase from Rhus vernicifera). The largest increase of Mw (108 600 Da) is reached when using SLS (17 800 Da) at 50 g/L and 30 U/mL of laccase from Trametes versicolor. The laccase polymerization of SLS can be improved by the use of a mediator. In this study, 5 mediators were studied for F1 polymerization by laccase from Trametes versicolor: acetosyringone (ASG), violuric acid (VLA), 1-hydroxy-benzotriazole (HBT), acetovanillone (ACV) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Results of F1 polymerization with mediators showed that only ASG and VLA lead to a higher molecular weight (7500 Da) compared with reactions carried without a mediator (6600 Da).

Sign in / Sign up

Export Citation Format

Share Document