Small Amounts Of Glucose Research Articles

Pectic polysaccharides from hawthorn: Physicochemical and partial structural characterization

The fruit of hawthorn (Crataegus pinnatifida Bge. var. major) is rich in pectic polysaccharides and has been used for centuries in China as food and herb. Hawthorn pectin (HP) recently has attracted rising attention due to the reported functional properties (e.g. gelling, emulsification) and health benefits towards the cardiovascular system. In this study, using hawthorn wine residue as raw material, a high methoxylated pectic polysaccharide HSP (degree of esterification up to 70%) was obtained by mild acid extraction (yield up to 20 wt%). Results from HPSEC coupled with triple detector revealed a widely dispersed (polydispersity index = 2) pectic polysaccharide with weight average molecular weight (Mw) of 111.7 kDa. Compared to pectin extracted from the hawthorn fruit, HSP showed a relatively lower molecular weight and higher polydispersity index (PDI), which suggested that the degradation of HP molecular chain during the wine-making processing (fermentation). Functionally, HSP demonstrated relatively high apparent viscosity but did not form gel in aqueous solution at concentrations up to 8 wt%. Structurally, HSP molecule was composed of over 70 mol% of 4-GalpA, with a small amount of glucose, galactose, xylose and arabinose. Under pectinase hydrolysis, over 95 wt% of the HSP was degraded into small fragments and monosaccharides; a small portion of relatively higher molecular weight rhamnose rich fragments were obtained from the hydrolytes. Combining both methylation analysis and 1D NMR spectroscopy, structural features of HSP were partially elucidated.

HYDROLYTIC HYDROGENATION OF INULIN WITH USE MAGNETIC-SEPARATE Ru-CONTAINING CATALYST

The combined hydrolysis and hydrogenation of inulin was studied on Ru-containing magnetically recoverable catalyst, using subcritical water as solvent. The Ru−Fe3O4−SiO2 catalysts are synthesized by incorporation of magnetite nanoparticles (NPs) in mesoporous silica pores followed by formation of 2 nm Ru NPs. The latter was obtained by thermal decomposition of ruthenium acetylacetonate in the pores. Magnetic properties of Fe3O4−SiO2 are typical for superparamagnetic iron oxide NPs of comparable size and allow to make a fast magnetic separation of the catalyst. The results of liquid nitrogen adsorption measurements are typical for mesoporous materials. The BET surface area of catalyst is 280 m2/g, what is allowed for mesoporous catalytic materials. The XPS spectra of Ru-Fe3O4-SiO2 demonstrate a good homogeneity of the sample. The catalyst was tested in hydrolytic hydrogenation of inulin. Inulin is hydrolyzed with formation of fructose and a small amount of glucose. There is a hydrogenation of fructose and glucose in hydrogen with receiving a mannitol and sorbitol, respectively. Mannitol is widely used in production of medicines and pharmaceutics, liquid fuel, the chemical and food industry, biotechnology and production of cosmetics. Mannitol presents in many plants and seaweeds. However, the extraction of mannitol from these raw materials is not a profitable process. Instead, fermentation and catalytic hydrogenation processes are used industrially. Nowadays, mannitol can be obtained by catalytic hydrogenation of monosaccharides like fructose or from glucose-fructose mixtures, using heterogeneous catalyst. During the researches key parameters of process, such as temperature and time of reaction, partial pressure of hydrogen are varied. At optimum reaction conditions: temperature of 150 °C, partial pressure of hydrogen of 60 bars in 45 min, – conversion of inulin was achieved of 100 %, a mannitol yield was 44.3 %. The used catalyst has shown high activity and stability in hydrothermal conditions. Stable magnetic properties of the catalyst cause his easy separation from reactionary mixture by means of external magnetic field.Forcitation:Ratkevich E.A., Manaenkov O.V., Matveeva V.G., Kislitza O.V., Sulman E.M. The hydrolytic hydrogenation of inulin catalyzed by Ru-containing magnetically recoverable catalyst. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 4-5. P. 76-81

The Role of Chain Structures on Enzymatic Hydrolysis of Potato and Sweet Potato Amylopectins

The relationships between the chain length distributions and enzymatic hydrolysis of potato amylopectin (PA) and sweet potato amylopectin (SPA) are studied to illustrate the effect of the internal branch structure of amylopectins on the digestibility of starches. The results show that SPA is more slowly hydrolyzed than PA due to the shorter internal chain length and a higher number of short chains with a higher density of branch leading to a more compact structure. Both PA and SPA display two phases in logarithm of slope plots, and PA has a higher rate constant k value than SPA. Using α‐amylase alone, a small amount of glucose is produced from PA and SPA, the primary products being maltose, maltotriose, and maltotetraose. Together with glucoamylase, glucose released from PA and SPA is significantly enhanced. Glucose release is about 3–10 times more than that released by α‐amylase alone. The digestible properties of starch and starch‐based products may be effectively regulated by controlling short:long B‐chains, density of branch, total chain length, and internal chain length of amylopectins.

Molecular cloning and biochemical characterization of an α-amylase family from Aspergillus niger

Background: α-Amylase is widely used in the starch processing, food and paper industries, hydrolyzing starch, glycogen and other polysaccharides into glucose, maltose and oligosaccharides. An α-amylase gene family from Aspergillus niger CBS513.88 encode eight putative α-amylases. The differences and similarities, biochemical properties and functional diversity among these eight α-amylases remain unknown. Results: The eight genes were cloned and expressed in Pichia pastoris GS115 by shaking-flask fermentation under the induction of methanol. The sequence alignment, biochemical characterizations and product analysis of starch hydrolysis by these α-amylases were investigated. It is found that the eight α-amylases belonged to three different groups with the typical structure of fungal α-amylase. They exhibited maximal activities at 30-40°C except AmyG and were all stable at acidic pH. Ca2+ and EDTA had no effects on the activities of α-amylases except AmyF and AmyH, indicating that the six amylases were Ca2+ independent. Two novel α-amylases of AmyE and AmyF were found. AmyE hydrolyzed starch into maltose, maltotriose and a small amount of glucose, while AmyF hydrolyzed starch into mainly glucose. The excellent physical and chemical properties including high acidic stability, Ca2+-independent and high maltotriose-forming capacity make AmyE suitable in food and sugar syrup industries. Conclusions: This study illustrates that a gene family can encode multiple enzymes members having remarkable differences in biochemical properties. It provides not only new insights into evolution and functional divergence among different members of an α-amylase family, but the development of new enzymes for industrial application.

Effect of organic carbon enrichment on the treatment efficiency of primary settled wastewater by Chlorella vulgaris

This work evaluated the performance of a microalgae treatment process for settled municipal wastewater in a laboratory setting under static culturing conditions, as an alternative to traditional, energy intensive secondary and tertiary wastewater treatment systems. Primary tank settled wastewater (PSW) was first enriched with small quantities of glucose (<300mgL−1) as an organic carbon source to facilitate the bioremediation by the mixotrophic microalga Chlorella vulgaris. Characterisation of the wastewater revealed significant reductions in NH3-N (from 28.9 to 0.1mgL−1) and PO4-P (from 3.2 to 0.1mgL−1) in just 2days. Additionally, the exogenous glucose appeared completely removed from the wastewater after the first day. These achieved levels of treatment in respect of both the NH3-N and PO4-P were much higher than those recorded without C. vulgaris treatment with or without glucose enrichment. This would mean that the microalgae were chiefly responsible for removing the inorganic nitrogen and phosphorus, while the naturally occurring heterotrophic organisms had consumed the carbonaceous matter. The reliability of this process was evaluated across a further three independent batches of PSW with varying compositions of these inorganics and chemical oxygen demand using alternative organic (glycerol) and inorganic (CO2) carbon sources. The efficiency of the microalgae treatment process at reducing NH3-N and PO4-P was consistent in PSW enriched with organic carbon, resulting in >90% reduction of the inorganic compounds in each batch. The results demonstrate that microalgal culturing processes to treat PSW in bioreactors without aeration are a key area to develop as an alternative biological treatment option.

Identification of an α-(1,4)-Glucan-Synthesizing Amylosucrase from Cellulomonas carboniz T26.

Amylosucrase, catalyzing the synthesis of α-(1,4)-glucan from sucrose, has been widely studied and used in carbohydrate biotransformation because of its versatile activities. In this study, a novel amylosucrase was characterized from Cellulomonas carboniz T26. The recombinant enzyme was overexpressed in Escherchia coli and purified by nickel affinity chromatography. It was determined to be a monomeric protein with a molecular mass of 72 kDa. The optimum pH and temperature for transglucosylation were measured to be pH 7.0 and 40 °C. The transglucosylation activity was significantly higher than the hydrolytic activity. The main product generated from sucrose was structurally determined to be α-(1,4)-glucan. A small amount of glucose was produced by hydrolysis, and sucrose isomers including turanose and trehalulose were generated as minor products. The ratio of hydrolytic, polymerization, and isomerization reactions was calculated to be 5.8:84.0:10.2. The enzyme favored production of long-chain insoluble α-glucan at lower temperature.

How Much and What Type of Protein Should a Critically Ill Patient Receive?

Protein loss, manifested as loss of muscle mass, is observed universally in all critically ill patients. Depletion of muscle mass is associated with impaired function and poor outcomes. In extreme cases, protein malnutrition is manifested by respiratory failure, lack of wound healing, and immune dysfunction. Protecting muscle loss focused initially on meeting energy requirements. The assumption was that protein was being used (through oxidation) as an energy source. In healthy individuals, small amounts of glucose (approximately 400 calories) protect muscle loss and decrease amino acid oxidation (protein-sparing effect of glucose). Despite expectations of the benefits, the high provision of energy (above basal energy requirements) through the delivery of nonprotein calories has failed to demonstrate a clear benefit at curtailing protein loss. The protein-sparing effect of glucose is not clearly observed during illness. Increasing protein delivery beyond the normal nutrition requirements (0.8 g/k/d) has been investigated as an alternative solution. Over a dozen observational studies in critically ill patients suggest that higher protein delivery is beneficial at protecting muscle mass and associated with improved outcomes (decrease in mortality). Not surprisingly, new Society of Critical Care Medicine/American Society for Parenteral and Enteral Nutrition guidelines and expert recommendations suggest higher protein delivery (>1.2 g/kg/d) for critically ill patients. This article provides an introduction to the concepts that delineate the basic principles of modern medical nutrition therapy as it relates to the goal of achieving an optimal management of protein metabolism during critical care illness, highlighting successes achieved so far but also placing significant challenges limiting our success in perspective.

An Acidic Exopolysaccharide from Haloarcula hispanica ATCC33960 and Two Genes Responsible for Its Synthesis.

A 1.1 × 106 Da acidic exopolysaccharide (EPS) was purified from an extremely halophilic archaeon Haloarcula hispanica ATCC33960 with a production of 30 mg L−1 when grown in AS-168 medium, which mainly composed of mannose and galactose with a small amount of glucose in a molar ratio of 55.9 : 43.2 : 0.9. Two glycosyltransferase genes (HAH_1662 and HAH_1667) were identified to be responsible for synthesis of the acidic EPS. Deletion of either HAH_1662 or HAH_1667 led to loss of the acidic EPS. The mutants displayed a different cell surface morphology, retarded growth in low salty environment, an increased adhesion, and swimming ability. Our results suggest that biosynthesis of the acidic EPS might act as an adaptable mechanism to protect the cells against harsh environments.

Expression, purification and characterization of an endoglucanase from Serratia proteamaculans CDBB-1961, isolated from the gut of Dendroctonus adjunctus (Coleoptera: Scolytinae)

Serratia proteamaculans CDBB-1961, a gut symbiont from the roundheaded pine beetle Dendroctonus adjunctus, displayed strong cellulolytic activity on agar-plates with carboxymethyl cellulose (CMC) as carbon source. Automatic genome annotation of S. proteamaculans made possible the identification of a single endoglucanase encoding gene, designated spr cel8A. The predicted protein, named Spr Cel8A shows high similarity (59–94 %) to endo-1,4-β-d-glucanases (EC 3.2.1.4) from the glycoside hydrolase family 8 (GH8). The gene spr cel8A has an ORF of 1113 bp, encoding a 371 amino acid residue protein (41.2 kDa) with a signal peptide of 23 amino acid residues. Expression of the gene spr cel8A in Escherichia coli yields a mature recombinant endoglucanase 39 kDa. Cel8A displayed optimal activity at pH 7.0 and 40 °C, with a specific activity of 0.85 U/mg. The enzyme was stable at pH from 4 to 8.5, retaining nearly 40–80 % of its original activity, and exhibited a half-life of 8 days at 40 °C. The Km and Vmax values for Spr Cel8A were 6.87 mg/ml and 3.5 μmol/min/mg of protein, respectively, using CMC as substrate. The final principle products of Spr Cel8A-mediated hydrolysis of CMC were cellobiose, cello oligosaccharides and a small amount of glucose, suggesting that Spr Cel8A is an endo-β-1,4-glucanase manifesting exo-activity. This is the first report regarding the functional biochemical and molecular characterization of an endoglucanase from S. proteamaculans, found in the gut-associated bacteria community of Dendroctonus bark beetles. These results contribute to improved understanding of the functional role played by this bacterium as a symbiont of bark beetles.

Structural characterization and anti-tumor effects of an inulin-type fructan from Atractylodes chinensis

A fructan (ACPS-1) with a molecular weight of 11.2kDa was isolated from Atractylodes chinensis rhizome and characterized by chemical derivatization, HPLC, GC–MS, FT-IR, and NMR. Structural analyses revealed that ACPS-1 is predominately composed of fructose and a small amount of glucose and a polymerization degree of about 53. The fructan was deduced to be an inulin-type fructan containing a linear backbone composed of (2→1)-linked β-d-Fruf residues. The in vitro antitumor activity of ACPS-1 was evaluated on four human cancer cell lines, including a cervical cancer cell line (Hela), two liver hepatocellular carcinoma cell lines (HepG2 and 7721), and an ovarian carcinoma cell line (Skov3). Results showed that ACPS-1 could significantly inhibit Hela, HepG2, and 7721 cell proliferation, especially HepG2, for which the fructan showed a proliferative inhibition rate as high as 87.40%. This result suggests that ACPS-1 may have anticancer potentiality against hepatocellular carcinoma and warrants further investigation.

Decoding glycome of Astragalus membranaceus based on pressurized liquid extraction, microwave-assisted hydrolysis and chromatographic analysis

Carbohydrates in herbs are a relatively untapped source of new drugs and health beneficial ingredients. Their analysis has been developed as a novel aspect in quality control and herbal glycomics. In this study, glycome of Astragalus membranaceus was decoded based on optimized pressurized liquid extraction (PLE), microwave-assisted acidic hydrolysis (MAAH) and comprehensive chromatographic approaches. Twelve saccharides including sucrose, galacturonic acid, mannitol, fructose, rhamnose, ribose, arabinose, fucose, xylose, mannose, glucose and galactose were quantitatively analyzed by GC–MS and HPLC–CAD (charged aerosol detectors). Different columns, including Prevail Carbohydrate ES, XBridge Amide and CARBOSep CHO-820 CA for HPLC–CAD analysis, were compared for evaluation of oligosaccharides. The polysaccharides in water extract of Astragalus membranaceus were characterized by high performance size exclusive chromatography (HPSEC) combined with multiple angle light scattering detection (MALSD) and refractive index detection (RID). The results showed that A. membranaceus contained more than 108.5mgg−1 free sucrose and small amounts of glucose 9.6–26.0mgg−1 and fructose 8.7–22.9mgg−1. While its polymeric carbohydrates were composed of glucose 71.0–162.3mgg−1, galacturonic acid 52.0–113.4mgg−1, arabinose 22.8–54.4mgg−1 and small amounts of galactose, rhamnose, xylose and mannose. CARBOSep CHO-820 CA showed its potential in simultaneously analyzing oligosaccharides and uronic acid, especially only the environment-friendly water mobile phase was used. HPSEC–MALSD–RID showed that there were three different molecular weight distributions of polysaccharides in A. membranaceus and the average molecular weight were 21901.1, 2038.5, and 353.4kDa. Hierarchical clustering analysis and principal component analysis demonstrated that A. membranaceus from different regions showed variations both in free and polymeric carbohydrates, which indicated that carbohydrates should be evaluated for the proper quality control of A. membranaceus. Rha, Ara, Xyl, Man and Gal were found to be the main elements for quality evaluation of polymeric carbohydrates in A. membranaceus by factor analysis. The strategy for decoding the glycome based on chromatographic approaches including GC–MS, HPLC–CAD and HPSEC–MALSD–RID after pressurized liquid extraction and microwave-assisted hydrolysis could be applied for carbohydrates profiling in herbs and beneficial for their quality control.

Moving to a Broader Concept of Quality of Glycemic Carbohydrates

Dietary carbohydrates are important in providing energy to humans, but carbohydrates are increasingly thought of as “bad” foods associated with obesity, diabetics and associated diseases. The objective of this report is in regard to how moderating glucose delivery profiles might be done to affect physiologic endpoints that may address these public health problems. Several projects were conducted related to this new concept. Small intestinal mucosal α-glucosidases, as the glucose generation point in digestion, were applied to hydrolyze starches and α-amylase hydrolysates in vitro to elucidate slower digesting components of starch. Alginate-based microsphere embedded with starch were developed to deposit glucose at different rates in the small intestine and glucosidase activity, feeding behavior, hypothalamic neuropeptides, and gastric emptying were examined in rat and mouse models. We also conducted studies to examine how distally release glucose affects gastric empty rate in humans. Overall, our results show that relatively small amount of glucose from glycemic carbohydrates in the diet delivered distally creates certain same and second meal physiological effects including modulation of gastric emptying rate of nutrients for digestion and absorption into the body, and reduced food intake accompanied by a lowering of the orexigenic neuropeptides of the hypothalamus. Dietary glucose, in this context, becomes a bioactive molecule as it triggers physiological responses, in addition to its major energy providing role. Our goal in future research is to develop food technologies, as well as to identify practical approaches, using whole grain or whole foods, or a mixture of food ingredient and whole food, for such carbohydrate quality health-related effects.

Structural characterization and immunostimulating activity of a levan-type fructan from Curcuma kwangsiensis

A fructan designated as CKNP with apparent molecular weight of 5.3kD was isolated from the hot water extract of Curcuma kwangsiensis through a combination of ion-exchange chromatography on DEAE 650M and gel filtration on Superdex G-200. CKNP was characterized by chemical derivatization as well as HPLC, GC, and GC–MS technologies. Structural studies revealed that CKNP is composed predominately of fructose (96.8%) and a small amount of glucose (3.2%) with a degree of polymerization (DP) of 30–31. It was deduced to be a levan-type fructan containing a backbone composed of (2→6)-linked β-d-Fruf residues and single β-d-Fruf residues as side chains branched at the O-1 position along the backbone. Preliminary in vitro bioactive tests on RAW 264.7 murine macrophage cells revealed that the levan-type fructan from C. kwangsiensis shows significant immunostimulating activity based on its ability to stimulate macrophage proliferation and enhance phagocytosis.

Characteristic hydrolyzing of megalosaccharide by human salivary α-amylase and small intestinal enzymes, and its bioavailability in healthy subjects

The digestibility of Megalosaccharide® (newly developed carbohydrate comprising α-1,4-glucosaccharide) was investigated in vitro and in vivo. Isomaltosyl-megalosaccharide® (IMS) and nigerosyl-megalosaccharide® (NMS) contain 20% and 50% of the megalosaccharide fraction (degree of polymerization (DP) 10–35), respectively. IMS was hydrolyzed readily by α-amylase to oligosaccharides (DP ≤ 7), and a small amount of glucose was produced from oligosaccharides by small intestinal enzymes (SIEs). NMS was partially hydrolyzed by α-amylase to oligosaccharides, and a small amount of glucose produced by SIEs. When IMS and NMS were treated by SIEs after treatment with human saliva α-amylase for a few minutes, IMS and NMS were hydrolyzed readily to glucose. Plasma levels of glucose and insulin upon ingestion of 50 g of IMS or NMS were elevated the same as those for 50 g of glucose, and breath hydrogen was not excreted. These results suggest that IMS and NMS are digestible carbohydrates.

The role of Aspergillus flavus veA in the production of extracellular proteins during growth on starch substrates

The aflatoxin-producer and opportunistic plant pathogenic, filamentous fungus Aspergillus flavus is responsible for the contamination of corn and other important agricultural commodities. In order to obtain nutrients from the host A. flavus produces a variety of extracellular hydrolytic enzymes. Interestingly, A. flavus amylase and protease activity are dependent on the global regulator veA, a gene known to regulate morphogenesis and secondary metabolism in numerous fungi. Analysis of starch degradation by fungal enzymes secreted into broths of starch- or corn kernel-based media showed a notable accumulation of glucose in samples of the A. flavus control strain while the deletion veA sample accumulated high levels of maltose and maltotriose and only a small amount of glucose. Furthermore, SDS-PAGE and proteomics analysis of culture broths from starch- or corn kernel-based media demonstrated differential production of a number of proteins that included a reduction in the amount of a glucoamylase protein in the veA mutant compared to the control strain, while an alpha-amylase was produced in greater quantities in the veA mutant. Quantitative real-time PCR and western blot analyses using anti-glucoamylase or alpha-amylase antisera supported the proteomics results. Additionally, an overall reduction in protease activity was observed in the veA mutant including production of the alkaline protease, oryzin, compared to the control strain. These findings contribute to our knowledge of mechanisms controlling production of hydrolases and other extracellular proteins during growth of A. flavus on natural starch-based substrates.

Construction of individual, fused, and co-expressed proteins of endoglucanase and β-glucosidase for hydrolyzing sugarcane bagasse

At least a combination of endoglucanase (EglII) and β-glucosidase (BglZ) is required for hydrolyzing crystalline cellulose. To understand the catalytic efficiency of combination enzymes for converting biomass to sugars, EglII and BglZ were constructed in the form of individual, fused as well as co-expression proteins, and their activities for hydrolyzing sugarcane bagasse were evaluated. The genes, eglII isolated from Bacillus amyloliquefaciens PSM3.1 earlier and bglZ from B. amyloliquefaciens ABBD, were expressed extracellularly in Bacillus megaterium MS941. EglII exhibited both exoglucanase and endoglucanase activities, and BglZ belonging to the glycoside hydrolase 1 family (GH 1) showed β-glucosidase activity. A combination of EglII and BglZ showed activity on substrates Avicel, CMC and sugarcane bagasse. Specifically for hydrolyzing sugarcane bagasse, fused protein (fus-EglII+BglZ), co-expression protein (coex-BglZ+EglII), and mixed-individual protein (mix-EglII+BglZ) produced cellobiose as the main product, along with a small amount of glucose. The amount of reducing sugars released from the hydrolyzing bleached sugarcane bagasse (BSB) using fus-EglII+BglZ and mix-EglII+BglZ was 2.7- and 4.2-fold higher, respectively, than steamed sugarcane bagasse (SSB), indicating the synergetic enzymes worked better on treated sugarcane bagasse. Compared with fus-EglII+BglZ and mix-EglII+BglZ, coex-BglZ+EglII released more mol reducing sugars from SSB, indicating the enzymes were potential for biomass conversion. Additionally, coex-BglZ+EglII acted on BSB 2.5-fold faster than fus-EglII+BglZ. Thus, coex-bglZ+eglII expression system was the best choice to produce enzymes for hydrolyzing sugarcane baggase.

New technologies aiding dietary programmes for weight control: the oral glucose spray

To determine whether the administration of small amounts of glucose through an oral spray device (GSD) facilitates weight loss in overweight/obese subjects involved in a lifestyle modification programme. We randomly assigned 56 overweight/obese subjects to either the treatment group (n = 32) or the control group (n = 24). All subjects in both groups followed a structured dietary programme of 6,280.2 kJ (1,500 kcal)/day and exercised minimum 150 min a week and were followed-up for a period of 60 days. Subjects assigned to the treatment group were asked to spray, during early symptoms of neuroglycopenia, 10 puffs by GSD. GSD is a device that delivers to the buccal mucosa 50 mg of glucose per puff. A mean weight loss of 3.5 ± 3.0 kg in GSD-treated group compared to 1.7 ± 2.1 kg in control group (p = 0.01) was observed. Significant differences regarding reduction of BMI (-1.3 ± 1.0 vs. -0.7 ± 0.8 kg/m2; p = 0.01) and waist circumference (-3.5 ± 3.2 vs. -0.9 ± 3.5 cm; p = 0.02) were also detected. A short-term use of GSD, in association with dietary restriction and exercise, is helpful in improving weight loss and in reducing waist circumference in overweight/obese subjects.

Characterization of Hemicelluloses Obtained from Partially Delignified Eucalyptus Using Ionic Liquid Pretreatment

Lignocellulosic biomass is a relatively inexpensive and abundant feedstock for biofuel production. The key to unlocking the recalcitrance of lignocelluloses is an effective pretreatment process. A promising new pretreatment method for lignocellulosic biomass is the use of ionic liquids (ILs). In this study, wood flour was partially dissolved in the novel ionic liquid 1-butyl-3-methylimidazolium acesulfamate ([BMIM]Ace) mixed with different organic solvents (1,4-dioxane, acetone, methanol, DMSO, and DMF) followed by precipitation in water. Hemicelluloses were successfully extracted from the carbohydrate-enriched residues by an alkaline ethanol solvent. Sugar analysis of the hemicellulosic fractions indicated that xylose (63.25-74.85%) was the major sugar component, while small amounts of glucose (4.85-14.40%) and galactose (4.49-7.32%) were also observed. Molecular weights of these fractions varied between 49.330 and 60.760 g/mol as determined by GPC. NMR studies revealed that the hemicelluloses had a backbone of β-(1→4)-linked-D-xylopyranosyl units and were branched mainly through 4-O-methyl-α-D-glucuronic acid. The thermal degradation behavior of the hemicellulosic fractions showed that the most significant degradation occurred between 242 and 300 °C.

Insulin infusion suppresses while glucose infusion induces Toll-like receptors and high-mobility group-B1 protein expression in mononuclear cells of type 1 diabetes patients

The purpose of this study was to determine whether an insulin infusion exerts an anti-inflammatory effect and whether the infusion of small amounts of glucose results in oxidative and inflammatory stress in patients with type 1 diabetes. Ten patients with type 1 diabetes were infused with either 2 U/h of insulin with 100 ml 5% dextrose/h to or just dextrose (100 ml/h) or physiological saline (100 ml/h) for 4 h after an overnight fast on three separate days. Blood samples were collected at 0, 2, 4, and 6 h. Insulin with glucose infusion led to the maintenance of euglycemia and a significant suppression of reactive oxygen species (ROS) generation, p47(phox) expression, Toll-like receptor (TLR)-4, TLR-2, TLR-1, CD14, high-mobility group-B1 (HMGB1), p38 mitogen-activated protein (MAP) kinase, c-Jun NH2-terminal kinase (JNK)-1, and platelet/endothelial cell adhesion molecule expression and a fall in serum concentrations of C-reactive protein, HMGB1, and rapid upon activation T cell expressed and secreted. Glucose infusion led to an increase in plasma glucose concentration from 115 (fasting) to 215 (at 4 and 6 h) mg/dl and to an increase in ROS generation, the expression of TLR-4, TLR-2, TLR-1, HMGB1, p38 MAP kinase, and JNK-1, and plasma concentrations of HMGB1. While insulin reduces indexes of oxidative and inflammatory stress in patients with type 1 diabetes, even small amounts of glucose (20 g over 4 h) induce oxidative and inflammatory stress. These effects are reflected in TLR, p38 MAP kinase, and HMGB1 expression. The induction of significant oxidative and inflammatory stress by small amounts of glucose in patients with type 1 diabetes may have important pathophysiological and therapeutic implications.

Role of the pentose phosphate pathway and the Entner–Doudoroff pathway in glucose metabolism of Gluconobacter oxydans 621H

Glucose catabolism by the obligatory aerobic acetic acid bacterium Gluconobacter oxydans 621H proceeds in two phases comprising rapid periplasmic oxidation of glucose to gluconate (phase I) and oxidation of gluconate to 2-ketogluconate or 5-ketogluconate (phase II). Only a small amount of glucose and part of the gluconate is taken up into the cells. To determine the roles of the pentose phosphate pathway (PPP) and the Entner-Doudoroff pathway (EDP) for intracellular glucose and gluconate catabolism, mutants defective in either the PPP (Δgnd, Δgnd zwf*) or the EDP (Δedd-eda) were characterized under defined conditions of pH 6 and 15 % dissolved oxygen. In the presence of yeast extract, neither of the two pathways was essential for growth with glucose. However, the PPP mutants showed a reduced growth rate in phase I and completely lacked growth in phase II. In contrast, the EDP mutant showed the same growth behavior as the reference strain. These results demonstrate that the PPP is of major importance for cytoplasmic glucose and gluconate catabolism, whereas the EDP is dispensable. Reasons for this difference are discussed.