Minimum Molecular Weight Research Articles

Hypoglycemic effect of orally administered resistant dextrins prepared with different acids on type 2 diabetes mice induced by high-fat diet and streptozotocin

A comparative study was performed to investigate the physicochemical properties and protective effects of hydrochloric acid-resistant dextrin (H-RD), citric acid-resistant dextrin (C-RD) and tartaric acid-resistant dextrin (T-RD) on the metabolic disorders and intestinal microbiota for type 2 diabetes mellitus (T2DM) mice. T-RD had the minimum molecular weight, with the highest short chain (DP 6–12) proportion and resistant starch content. After 4-week intervention with the three resistant dextrins, the body weight and fasting blood glucose of T2DM mice were improved significantly, accompanied by the reduction of serum indexes (TG, TC, LDL-C, ALT, AST, CRE, BUN, FINS, and GSP), but the serum HDL-C and liver glycogen levels increased. Among the three RDs intervention groups, T-RD showed the most significant improvement, followed by C-RD and finally H-RD. The 16 s rDNA results indicated that oral administration of resistant dextrins favored the proliferation of specific gut microbiota, including Faecalibaculum, Parabacteroides and Dubosiella, and reduced the ratio of Firmicutes/Bacteroidota, which is beneficial for reducing insulin resistance. Herein, the findings supported that the resistant dextrins exhibited a remission effect on T2DM, providing a basis for the development of functional food adjuvants for T2DM treatment.

What Is the Molecular Weight of "High" Molecular Weight Dissolved Organic Matter?

The use of ultrafiltration to isolate high molecular weight dissolved organic matter (HMWDOM) from seawater is a fundamental tool in the environmental organic chemist's toolbox. Yet, important characteristics of HMWDOM relevant to its origin and cycling, such as its molecular weight distribution, remain poorly defined. We used diffusion-ordered NMR spectroscopy coupled with mixed-mode chromatography to separate and characterize two major components of marine HMWDOM: acylpolysaccharides (APS) and high molecular weight humic substances (HS). The molecular weights (MWs) of APS and HS both fell within distinct, narrow envelopes; 2.0-16 kDa for APS and 0.9-6.5 kDa for HS. In water samples from the North Pacific Ocean the average MW of both components decreased with depth through the mesopelagic. However, the minimum MW of APS was >2 kDa, well above the molecular weight cutoff of the ultrafilter, suggesting APS removal processes below 2 kDa are highly efficient. The MW distribution of APS shows only small variations with depth, while the MW distribution of HS narrowed due to removal of HMW components. Despite the narrowing of the MW distribution, the concentration of HS did not decrease with depth between 15 and 915 m. This suggests that HMW HS produced in surface waters was either degraded into lower MW compounds without significant remineralization, or that HMW HS was remineralized but replaced by an additional source of HS in the mesopelagic ocean. Based on these results, we propose potential pathways for the production and removal of these major components of HMWDOM.

Minimum Molecular Weight and Tie Molecule Content for Ductility in Polyethylenes of Varying Crystallinity

Minimum Molecular Weight and Tie Molecule Content for Ductility in Polyethylenes of Varying Crystallinity

Production of Copepod Luciferases via Baculovirus Expression System.

Secreted copepod luciferases (CopLucs) represent highly homologous enzymes which catalyze the oxidation of a low molecular weight substrate, coelenterazine, with the emission of blue light (λmax=485-488nm), that is called bioluminescence (BL). The well-studied Gaussia (GLuc) and Metridia (MLuc) luciferases originally cloned from the marine copepods Gaussia princeps and Metridia longa belong to the group of the smallest natural luciferases. Their minimal molecular weight, high luminescent activity, cofactor-independent BL, and the ability to be secreted due to the own signal peptide open up the horizons for genetic engineering of CopLuc-based sensitive biosensors for in vivo imaging and in vitro analytical applications. The "standard" soluble bacterial expression of the recombinant CopLucs and luciferase-based hybrid proteins is hampered by the presence of high amounts of intramolecular disulfide bonds (up to 5permolecule). Here, we describe the universal protocol for highly effective secreted expression of disulfide-rich CopLucs using their own signal peptide in insect cells and their purification from serum-free culture medium. The suggested protocol allows obtaining high-purity CopLucs folded in their native form with the yield of up to 5mg per liter.

Structural properties and antioxidant activity of polysaccharides extracted from Laminaria japonica using various methods

Polysaccharides in brown algae, including the kelp Laminaria japonica, are economically important to both food and pharmaceutical industries. The method used to extract polysaccharides significantly influences their characteristics and functions. In this study, L. japonica polysaccharides (LJP) were extracted using four techniques: hot-water extraction (HWE), ultrasound-assisted extraction (UAE), enzyme-assisted extraction (EAE), and acid-assisted extraction (AAE). The highest yield (9.73 ± 0.29 %) and sulfate content (12.47 ± 0.79 %) were obtained via UAE, whereas EAE yielded the highest total carbohydrate content (53.50 ± 1.38 %), with an extraction yield of 9.12 ± 0.13 %. The minimum molecular weight (Mw) was found after AAE, whereas a higher Mw was obtained after EAE and HWE, and a homogeneous Mw was obtained after UAE. All four LJP extracts contained a helix-coil conformation based on Congo red staining, with five monosaccharides, fucose, galactose, mannose, xylose, and glucuronic acid, in varying proportions. Polysaccharides extracted via EAE and UAE exhibited higher antioxidant activity with morphological and conformation changes. A significant correlation was noted between sulfate content and antioxidant activity, and antioxidant capacity was positively correlated to mannose content rather than uronic acid. The results indicate UAE to be the best of the four extraction methods for polysaccharides with homogeneous Mw and high antioxidant activity. This study sheds light on the effects of extraction processes on the physiochemical characteristics of polysaccharides and the relationship between chemical composition and antioxidant activities.

Removal of ibuprofen by sodium alginate-coated iron-carbon granules combined with the ultrasound and Fenton technologies: influencing factors and degradation intermediates.

This study focuses on the preparation of sodium alginate-coated iron-carbon granules (FeCGs) and their capacity to remove ibuprofen (IBU) by combining Fenton and ultrasound technologies. The preferred preparation conditions are as follows: 2% (w/v) sodium alginate, 10% (w/v) iron fillings and biochar, and used CaCl2 as the cross-linking agent. 74.72% of IBU was removed by ultrasound/FeCG under 10 g/L FeCG and 250 W ultrasound power. Fenton/FeCG could remove 92.41% of IBU under 10 g/L FeCG and 2 mM H2O2. Under the above experimental conditions, ultrasound/FeCG has higher reaction speed (9.44 × 10-3 min-1) than Fenton/FeCG (4.95 × 10-3 min-1). However, Fenton/FeCG could remove more TOC than ultrasound/FeCG. During the reaction using the Fenton/FeCG system, 11 degradation intermediates were detected, but only 7 intermediates were produced by the ultrasound/FeCG system. A common single-chain product C5H10O3 formed by IBU degradation was detected in the reaction products during Fenton/FeCG reaction, which benzene ring structure was destroyed; however, the minimum molecular weight of the product detected using the ultrasound/FeCG system was that of C8H10O; the benzene ring structure of IBU is not destroyed. This study provides guidance in the preparation of sodium alginate-coated FeCGs, evaluating the applicability of Fenton/FeCG and ultrasound/FeCG, which was meaningful for organic pollution wastewater treatment.

Physicochemical and Structural Characteristics of Soybean Protein Isolates Induced by Lipoxygenase-Catalyzed Linoleic Acid Oxidation during In Vitro Gastric Digestion.

The effects of oxidation on the gastric digestion properties of soybean protein isolates (SPIs) in a model of lipoxygenase (LOX)-catalyzed linoleic acid (LA) oxidation system and the multiscale structural characterization of SPI hydrolysate were investigated. Results indicated that the feature of SPI hydrolysate is dependent upon the degree of oxidation. Pepsin hydrolysis caused a red shift in fluorescence intensity and a reduction in surface hydrophobicity and diminished the particle size of SPI hydrolysate during gastric digestion. Compared with the control, mild oxidation was beneficial to protein unfolding and gastric digestibility, as manifested by minimal molecular weight (MW) distribution >50 kDa (32.34%) and smaller peptide fragments under scanning electron microscopy. However, severe oxidation brought about 39.47% loss of free amino acids. It was interesting to find that glycinin was more vulnerable to pepsin hydrolysis after oxidation as compared to the native SPI. Overall, the moderately oxidized SPI appeared to be digested to a greater extent.

Structural and physicochemical properties of lotus seed starch nanoparticles

Lotus seed starch (LS) was enzymatically hydrolyzed by pullulanase, β-amylase and α-amylase to obtain three types of starch nanoparticles (SNPs): P-SNPs, β-SNPs and α-SNPs, respectively. The structure and physicochemical properties of lotus seed starch nanoparticles (LS-SNPs) were systematically studied by Laser particle size analysis, Scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectrometry, Nuclear magnetic resonance (NMR) and Gel permeation chromatography (GPC). The results showed that compared to LS (10,466.7 ± 230.9 nm), the D [3,2] of P-SNPs were (334.7 ± 16.2), which indicated that LS was decomposed into LS-SNPs with low degree of polymerization. P-SNPs showed the highest efficiency, with 81.74% of samples reaching the nanoscale. The particle size order was LS > β-SNPs (α-SNPs) > P-SNPs. XRD results showed P-SNPs had the highest crystallinity 65.07%. During preparation of LS-SNPs, crystal region was destroyed, and double helix structure became stronger, but no new functional groups were introduced. P-SNPs had the smallest amorphous area and also showed a minimal molecular weight and the broadest molecular weight distribution. P-SNPs had the smallest particle size and the highest crystallinity, so P-SNPs were the best of all LS-SNPs.

Rapidly and highly efficient degradation of tetracycline hydrochloride in wastewater by 3D IO-TiO2-CdS nanocomposite under visible light

ABSTRACT Tetracycline hydrochloride as an environmental pollutant is biologically toxic and highly difficult to degrade. To solve this problem, an efficient catalyst IO-TiO2-CdS composite with honeycomb-like three-dimensional (3D) inverse opal TiO2 (IO-TiO2) and cadmium sulphide (CdS) was synthesized and applied in the degradation of tetracycline hydrochloride in this paper. More than 99% of the tetracycline hydrochloride (30 mg/L) can be degraded by IO-TiO2-CdS (30 mg) within 20 min under visible light irradiation. Surprisingly, the naphthol rings can be opened and degraded to alkane with a minimum molecular weight of 60, which is the smallest fragment among all publications. The three-dimensional ordered macroporous (3DOM) structure of IO-TiO2 improves the utilization of light via the slow photon effect. Meanwhile, the addition of CdS enhances the degradation efficiency of tetracycline by broadening the range of absorption spectrum and improving the separation of charge carrier on the catalyst. In addition to the degradation of tetracycline hydrochloride, IO-TiO2-CdS also shows a good degradation efficiency of Rhodamine B (RhB). This work provides a promising approach to construct visible light response photocatalysts with non-noble metal for efficient degradation of wastewater pollutants.

Benzofused hydroxamic acids: useful fragments for the preparation of histone deacetylase inhibitors. Part 2: 7-fluorobenzothiophenes and benzofurans.

In the search for a new class of histone deacetylase inhibitors, we prepared a series of very simple benzofused hydroxamic acids to find an anchoring fragment of minimal molecular weight: they showed very good ligand efficiencies. Following these findings, classical fragment growing work was performed to increase binding energy and selective cytotoxicity. In the second phase of the work, information from the SARs of the benzothiophene series and data available in literature, we explored the in vitro pharmacological properties of the 6-substituted-7-fluoro-benzothiophene hydroxamates and the 5-susbtituted-benzofuran hydroxamates.

Benzofused hydroxamic acids: Useful fragments for the preparation of histone deacetylase inhibitors. Part 1: Hit identification

In the search for a new class of histone deacetylase inhibitors, we prepared a series of simple benzofused hydroxamic acids to find an anchoring fragment of minimal molecular weight. These initial hits, all belonging to the benzothiophene class, showed very good ligand efficiencies. Following these findings, a classical fragment growing approach was performed to increase binding affinity and cytotoxicity.

A new method for encapsulating hydrophobic compounds within cationic polymeric nanoparticles

Here we present the newly developed “solvent exchange” method that overcomes the challenge of encapsulating hydrophobic compounds within nanoparticle of water soluble polymers. Our studies involved the model polymer polyvinylpyrrolidone (PVP) and the hydrophobic dye Nile red. We found that the minimum molecular weight of the polymer required for nanoparticle formation was 49 KDa. Dynamic Light Scattering (DLS) and Cryo-Transmission Electron Microscopy (cryo-TEM) studies revealed spherical nanoparticles with an average diameter ranging from 20 to 33 nm. Encapsulation efficiency was evaluated using UV spectroscopy and found to be around 94%. The nanocarriers were found to be highly stable; less than 2% of Nile red release from nanoparticles after the addition of NaCl. Nanoparticles containing Nile red were able to penetrate into glioma cells. The solvent exchange method was proved to be applicable for other model hydrophobic drug molecules including ketoprofen, ibuprofen and indomethacin, as well as other solvents.

Interpolyelectrolyte complexes based on hyaluronic acid-block-poly(ethylene glycol) and poly-l-lysine

The preparation of spherical, nanosized interpolyelectrolyte complexes by the interaction of hyaluronic acid-block-poly(ethylene glycol) (HA-b-PEG) with poly-L-lysine (PLL) at a stoichiometric charge-to-charge ratio is described. The complexation was studied by dynamic light scattering and cryogenic transmission electron microscopy for HA-b-PEG with different lengths of the HA and PEG blocks. A minimal molecular weight of the HA block (ca. 9 kDa) is necessary for efficient complexation, while a minimal molecular weight of the PEG block (ca. 5 kDa) is needed to prevent macroscopic aggregation. The formed nanoassemblies have hydrodynamic radii ranging from 45 to 150 nm with very low dispersity indices (D.I. = 0.02–0.05). They appear as soft objects with a nanogel structure and pronouncedly swell on addition of NaCl. The increasing ionic strength leads to disruption of the complexes above ca. 120–160 mM of NaCl. Decreasing the ionic strength by dialysis reforms the nanogels, demonstrating the reversibility of nanogel formation. Crosslinking with carbodiimide leads to nanoassemblies with a very well defined structure and high stability against ionic strength.

Extraction conditions of Antheraea mylitta sericin with high yields and minimum molecular weight degradation

Although the technique for extracting the Bombyx mori sericin has been extensively known, the extraction of sericin from wild-silkworm cocoons is not yet standardized. The aim of this study was to find the optimal conditions for the extraction of sericin from Antheraea mylitta cocoons, with high yields and minimum degradation. We attempted to apply various protocols for the extraction of the A. mylitta sericin (AmS). Among these, we found that the extraction of AmS with a sodium carbonate solution exhibited the highest yield except the conventional soap-alkali extraction. To find the optimal conditions for the AmS extraction with the sodium carbonate, we changed the concentration of sodium carbonate and the treatment time. With an increase in the sodium carbonate concentration and the extraction time, the yield of AmS increased, but the molecular weight (MW) of AmS decreased. Considering the yield, molecular weight distribution (MWD) and amino acid composition of AmS, we suggest that the optimal conditions for the AmS extraction require treatment with 0.02M sodium carbonate and boiling for 60min.

Influence of Polymer Architecture and Molecular Weight of Poly(2-(dimethylamino)ethyl methacrylate) Polycations on Transfection Efficiency and Cell Viability in Gene Delivery

Nonviral gene delivery with the help of polycations has raised considerable interest in the scientific community over the past decades. Herein, we present a systematic study on the influence of the molecular weight and architecture of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) on the transfection efficiency and the cytotoxicity in CHO-K1 cells. A library of well-defined homopolymers with a linear and star-shaped topology (3- and 5-arm stars) was synthesized via atom transfer radical polymerization (ATRP). The molecular weights of the polycations ranged from 16 to 158 kDa. We found that the cytotoxicity at a given molecular weight decreased with increasing number of arms. For a successful transfection a minimum molecular weight was necessary, since the polymers with a number-average molecular weight, M(n), below 20 kDa showed negligible transfection efficiency at any of the tested polyelectrolyte complex compositions. From the combined analysis of cytotoxicity and transfection data, we propose that polymers with a branched architecture and an intermediate molecular weight are the most promising candidates for efficient gene delivery, since they combine low cytotoxicity with acceptable transfection results.

The effect of membrane formation parameters on performance of polyimide membranes for organic solvent nanofiltration (OSN). Part C. Effect of polyimide characteristics

Asymmetric membranes for organic solvent nanofiltration (OSN) were fabricated from polyimides (PI) synthesised by polycondensation reactions. The effect of molecular weight and chemical structure of the synthesised PIs on the PI OSN membrane formation and performance was investigated. This work is the final part of a three parts study seeking a better understanding of how membrane formation parameters affect membrane performance. During a co-polymerisation reaction 3,3′,4,4′-benzophenone tetracarboxylic dianhydride was reacted with various diisocyanates i.e. toluene-2,4-diisocyanate, 4,4′-methylenebis(phenyl isocyanate), 3,3′-dimethoxy-4,4′-biphenyl diisocyanate, and isophorone diisocyanate. It has been shown that the rejection of PI OSN membranes is not influenced by the molecular weight of the PI which varied between 30,000 and 70,000 Da. However, there is a minimum molecular weight (35,000 Da) required to cast defect free membranes with good mechanical strength for OSN applications. Likewise, too high PI molecular weight (80,000 Da) results in too viscous dope solution which hinders membrane casting. Structural changes in the PI and the method of polymerisation (block vs random) were found to affect both flux and rejection of the membranes. The use of the random PI resulted in the formation of more open membranes having lower rejection and higher flux.

Purification, characterization and toxicity of a mannose-binding lectin from the seeds of Treculia africana plant

In this study, a mannose-specific, homodimeric lectin from the seeds of Treculia africana was purified, characterized and its adverse effects were investigated in mice. The purification protocol involved anionic exchange chromatography on DEAE-Cellulose followed by gel filtration on Sephadex G-100. The hemagglutinating activity of lectin towards human erythrocytes was sensitive to inhibition by D-mannose. Treatment of the protein with EDTA exerted no inhibitory effect; however, analysis of metal content by atomic absorption spectroscopy revealed the presence of Cu2+, Fe3+, and Mg2+. The results obtained showed that the lectin possesses maximum hemagglutinating activity towards human erythrocytes activity over the pH range 3–7.2 and is relatively thermostable up to 50°C. Periodic acid Schiff's (PAS) reagent staining showed that the protein was non-glycosylated while its amino acid composition analysis revealed that the protein contained 155 residues per subunit. The subunit had a minimal molecular weight of 22,139 Daltons, while the native molecular weight was estimated to be 41,000 Daltons. The lectin was found to be moderately toxic to mice with an LD50 of 47.21 µg g−1 body weight while, histopathological analysis showed no treatment related effects in any of the organs examined.

Purification and properties of membrane-bound methane hydroxylase from Methylococcus capsulatus (Strain M)

Membrane fraction of Methylococcus capsulatus (strain M) were treated with [14C]acetylene, an affinity label binding to the active center of membrane-bound methane monooxygenase (MMO). High-purity particulate form of methane hydroxylase (pMH) was obtained by ion exchange and hydrophobic chromatography. According to SDS-PAGE data, the enzyme contained three polypeptides with molecular weights of 47 (alpha), 27 (beta), and 25 (gamma) kDa in the ratio 1:1:1. The radiolabel was contained in the beta-subunit of pMH. The protein contained 1 or 2 atoms of nonheme iron and 2-4 atoms of copper per a minimum molecular weight of 99 kDa. This protein did not oxidize methane or propylene in the presence of NADH but was able to oxidize low quantities of methane in the presence of duroquinol. It was established that methanol dehydrogenase (MD) and NADH oxidoreductase (NADH-OR) are peripheral membrane proteins. Possible causes of low activity of high-purity methane hydroxylase are discussed.

A generalized model for the film growth during the constant voltage electro-deposition of resin dispersions

A generalized model was derived to explain the electro-deposition behavior of a range of acrylic electro-deposition resins having different minimum film formation temperatures and different molecular weights. The influence of co-solvent on the electro-coagulation and film formation of the studied resins has also been verified based on the variations of the model parameters. It was found that the generalized model could well describe the constant voltage electro-deposition behavior of resin dispersions.

Removal of API's (Active Pharmaceutical Ingredients) from Organic Solvents by Nanofiltration

The removal of 5 specific active pharmaceutical ingredients (API's) with molecular weight of 189, 313, 435, 531, and 721, respectively, from toluene, methylene chloride, and methanol was studied by using solvent resistant nanofiltration. Three membranes of the StarMem series (120, 122, and 228), with cut‐off values of 200, 220, and 280 respectively, were used in the experiments. Although the rejections expected from the size difference between solutes and membrane pores are high, the results largely depended on the solvent used. For toluene, rejections were rather small, due to the low molecular weight of the solutes of interest (all API's except for the largest compound). Modelling of the rejection curve showed that the minimum molecular weight of a solute to obtain a rejection of 90% in toluene with the membranes used, is ca. 600. The application in methylene chloride was unsuccessful due to partial dissolution of the membrane top layer; other polymeric membranes such as the Solsep series might be more successful. The rejections in methanol were sufficiently high (>90%) to allow implementation: the rejection can be significantly increased by using a module design with double membrane passage and recirculation of the retentate, as was calculated from mass balances. A comparison of a (single pass) nanofiltration system with a throughput distillation unit, currently in use, showed that the energy consumption is 200 times lower in the nanofiltration system.