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Journal of Agricultural and Food... Feb 1999A novel procedure to determine the molecular weight (MW) and MW distributions for various agars is described. The MW values of commercial agars, an agarose, an...
A novel procedure to determine the molecular weight (MW) and MW distributions for various agars is described. The MW values of commercial agars, an agarose, an agaropectin, and hydrolyzed agaroses were determined by size exclusion chromatography-low angle laser light scattering, using 4.0 M guanidine hydrochloride as eluent to avoid gelation. The MW for the commercial agars was between 106 400 and 243 500 with polydispersity between 1.283 and 6. 600. The MW of the agarose separated from a commercial agar was lower than that of the agaropectin. To prepare agaroses with different MW values, the obtained agarose was hydrolyzed. The MW of the agarose decreased with hydrolysis time, and the polydispersity, on the contrary, increased. The glass transition temperature (T(g)) of agarose with different MW values and that of agaropectin were measured by differential scanning calorimetry. The T(g) of the agarose was higher than that of the agaropectin with higher MW. The T(g) of agarose increased with MW.
Topics: Agar; Calorimetry, Differential Scanning; Chemical Phenomena; Chemistry, Physical; Molecular Weight
PubMed: 10563919
DOI: 10.1021/jf980713p -
Analytical Biochemistry Sep 2023Protein electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulfate (SDS-PAGE) is one of the most commonly performed procedures in biochemical...
Protein electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulfate (SDS-PAGE) is one of the most commonly performed procedures in biochemical laboratories. It requires the use of molecular weight (MW) markers as an internal technical control and to determine the migration rate of a particular protein. In this work, we describe a simple method for preparing "homemade" prestained protein markers using readily available cow's milk and chicken egg white proteins without the need of any major protein purification step, and produce prestained MW markers ranging from 19 to 98 kDa.
Topics: Proteins; Electrophoresis, Polyacrylamide Gel; Molecular Weight; Sodium Dodecyl Sulfate
PubMed: 37414351
DOI: 10.1016/j.ab.2023.115231 -
Macromolecular Rapid Communications Nov 2021This article presents a fast, straightforward synthesis approach to polymerize alternating multiblock copolymers, ultra-high molecular weight (UHMW) (homo)polymers as...
This article presents a fast, straightforward synthesis approach to polymerize alternating multiblock copolymers, ultra-high molecular weight (UHMW) (homo)polymers as well as precursors for complex macromolecular topologies such as comb or barbwire architectures. The one-pot synthesis strategy proposed in this work is based on anionic polymerization via a bifunctional initiator and the subsequent linking of macro dianions with a bifunctional linker, additionally overcoming the limitations associated with the monomer reactivity. Thus, the synthetic route guarantees the repeating size of polymer blocks and an equal distribution of functional groups in precursors for complex topologies. Dianions of polystyrene (PS), polyisoprene-b-polystyrene-b-polyisoprene, and poly-2-vinylpyridine-b-polystyrene-b-poly-2-vinylpyridine are linked with -dibromo-para-xylene to UHMW and multiblock copolymers. Multiblock copolymers with on average up to 50 well-defined alternating A and B blocks are accessible within 15 min.
Topics: Anions; Macromolecular Substances; Molecular Weight; Polymerization; Polymers
PubMed: 34528318
DOI: 10.1002/marc.202100448 -
Macromolecular Rapid Communications Jul 2022Poly(acrylic acid) (PAA) is produced on an industrial scale and widely-used in applications such as personal care products and cleaning formulations that end up...
Poly(acrylic acid) (PAA) is produced on an industrial scale and widely-used in applications such as personal care products and cleaning formulations that end up "down-the-drain." Relatively high molecular weight PAA is considered poorly biodegradable, but little is known about the biodegradability of low molecular weight PAA at the wastewater treatment plant according to current regulatory and industrial Organization for Economic Co-operation and Development (OECD) standards. The synthesis, separation, and characterization of a series of ultralow dispersity PAA oligomers (i.e., Đ < 1.10) in the molecular weight range M ≈ 350-1200 Da and the results of biodegradability testing are reported. Miniaturized, high-throughput screening studies in a parallel respirometer reveals a strong trend toward lower biodegradation at higher molecular weight; these results are confirmed and expanded using standardized method OECD 301F. Biodegradability reaches ≈40% at M = 380 Da, ≈26% at M = 770 Da, and ≈17% at M = 1190 Da for discrete polyacid oligomers. These data not only shed light on potential biodegradation mechanisms for linear PAA, but also may inspire the future design of biodegradable PAA-containing macromolecules.
Topics: Acrylic Resins; Biodegradation, Environmental; Molecular Weight
PubMed: 35271740
DOI: 10.1002/marc.202100773 -
Rapid Communications in Mass... 2001Process improvements in the synthesis of therapeutic agents and their intermediates are often facilitated by identification of reaction by-products. Analysis by liquid...
Process improvements in the synthesis of therapeutic agents and their intermediates are often facilitated by identification of reaction by-products. Analysis by liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization is a powerful approach for obtaining molecular weight information for these compounds. Such analyses are well suited for 'open-access' mass spectrometry using generic chromatographic conditions, provided spectral interpretation for unknown compounds is facile. We have developed a software application (MassAssign) that facilitates automated data processing and molecular weight assignment for chromatographic peaks detected by any standard ultraviolet-visible wavelength detector. The program assigns [M + H](+) ions (and thus molecular weight) in the mass spectra using predetermined criteria. This evaluation process differentiates [M + H](+) ions from other signals in a complex mass spectrum such as those resulting from chromatographic coelution or the presence of multiple species (i.e., fragment ions, singly charged ions, doubly charged ions, adduct ions, proton-bound dimers, etc.). Once the program has evaluated all ions in a mass spectrum that exceed a preset abundance threshold, MassAssign reports either a numeric value-indicating the chromatographic peak consists of a single component having the displayed molecular weight, 'MC'-indicating the peak consisted of multiple components, or 'ND'-that a molecular weight could not be determined unequivocally. The performance of the program was evaluated by comparing mass assignments made by MassAssign against manual interpretation for 55 samples analyzed by positive electrospray ionization using a generic HPLC method. Correct molecular weight assignments were obtained in 90% of the cases.
Topics: Algorithms; Autoanalysis; Molecular Weight; Pharmaceutical Preparations; Spectrometry, Mass, Electrospray Ionization; Spectrophotometry, Ultraviolet
PubMed: 11746916
DOI: 10.1002/rcm.519 -
Journal of the American Chemical Society Dec 1945
Topics: Hydrocarbons; Molecular Weight
PubMed: 21005693
DOI: 10.1021/ja01228a057 -
Postepy Biochemii 1967
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The New England Journal of Medicine Apr 1974
Topics: Molecular Weight; Weights and Measures
PubMed: 4816998
DOI: 10.1056/nejm197404252901725 -
Chemistry, An Asian Journal Aug 2022Low-molecular-weight hydrogelators containing stearoyl, glycine, and D-glucamine moieties with or without methyl groups were synthesized to prepare chemically tuned...
Low-molecular-weight hydrogelators containing stearoyl, glycine, and D-glucamine moieties with or without methyl groups were synthesized to prepare chemically tuned molecular hydrogels. To evaluate the role of hydrogen bonding of hydrogelators in molecular hydrogel formation, the author has newly synthesized hydrogelators with or without methyl groups at their N-H in amide groups, contributing to the hydrogen bond formation in fiber in molecular hydrogels. The obtained hydrogels exhibited improved thixotropic performance with tunable softness, exhibiting pseudo-reversible thixotropic cycles that depended on the methyl substitution positions in the hydrogelators. To change the hydrogen bonds' positions by chemical modification has made it possible to tune the mechanical properties of molecular gels.
Topics: Hydrogels; Hydrogen Bonding; Molecular Weight
PubMed: 35703338
DOI: 10.1002/asia.202200461 -
The Biochemical Journal Jul 1978Concentrated solutions of low-molecular-weight DNA (Mw=35000) with a known molecular-weight distribution can be prepared in several hours, and require no additional...
Concentrated solutions of low-molecular-weight DNA (Mw=35000) with a known molecular-weight distribution can be prepared in several hours, and require no additional fractionation procedures. This is achieved by sonication of the DNA in 1.0 M-NaCl at high power at 0--2 degrees C. No denaturation of the DNA is detectable, even after 8h of continuous sonication. After 2h, the molecular-weight distribution of the total DNA sample is that of the most probably Schulz distribution, described by-Mn:-Mw:-Mz ...=1:2:3 ...etc. Such a molecular-weight distribution is expected for a random break-up of indefinitely long macromolecules and indicates that the sonication process is essentially by random double-strand scission. DNA was also sonicated in the presence of ligands capable of modifying the DNA tertiary structure. The results support the idea that inflexibility of the DNA is required for efficient sonic degradation.
Topics: Chromatography, Gel; DNA; Ligands; Molecular Weight; Sonication; Time Factors; Ultrasonics
PubMed: 687366
DOI: 10.1042/bj1730179