Structural elucidation of the O-antigenic polysaccharide from enterohemorrhagic (EHEC) Escherichia coli O48:H21

The structure of the antigenic O-polysaccharide (O-PS) of the lipopolysaccharide (LPS) produced by the enterohemorrhagic strain of Escherichia coli O48:H21 (EHEC) has been elucidated. The O-PS obtained by mild acid hydrolysis of the LPS had [alpha]D +95 (water) and was composed of L-rhamnose (L-Rha), D-galactose (D-Gal), 2-amino-2-deoxy-D-glucose (D-GlcN), 2-amino-2-deoxy-D-galactose (D-GalN), and D-galacturonic acid (D-GalA) (1:1:1:1:1). From the results of methylation analysis, mass spectrometry, 2D NMR, and DOC-PAGE, the O-PS was shown to be a high molecular mass polymer of a repeating pentasaccharide unit having the structure: [structure: see text]. The D-Gal pA non-reducing end groups in the O-PS were partially O-acetylated (approximately 30%) at the O-2 and O-3 positions and the degree of acetylation was variable from batch to batch cell production.     

Pharmacological evaluation of tea polysaccharides with antioxidant activity in gastric cancer mice

Tea polysaccharides were fractionated by Sephadex G-100 gel permeation chromatography. The results showed that tea polysaccharides were mainly composed of TF-1, TF-2 and TF-3. The average molecular weights of TF-1, TF-2 and TF-3 determined by high-performance gel permeation chromatography (HPGPC) and high performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD) were 231,568Da, 46,278Da and 7251Da, respectively. The monosaccharide composition of Renshen polysaccharides was evaluated by GC. TF-1 was composed of glucose, mannose, xylose with molar ratio of 1:3.2:1.4. TF-2 and TF-3 consisted of glucose, xylose and glucose, xylose, arabinose with molar ratios of 1:1.7 and 1:2.5:0.9, respectively. TF-1 contained mannose as main sugar component and TF-2 was rich in xylose, whereas TF-3 was rich in xylose. In addition, tea polysaccharides could decrease stomach malondialdehyde (MDA) level, serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels, increased serum immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM), interleukin-2 (IL-2), interleukin-4 (IL-4), interleukin-10 (IL-10) levels, and stomach antioxidant enzymes activities in gastric cancer mice.     

Sphingomyelinase activity associated with human plasma low density lipoprotein

Isolated human plasma low density lipoprotein (LDL) was observed to possess sphingomyelinase activity. Accordingly, the formation of ceramide was catalyzed by LDL at 37 degrees C using tertiary liposomes composed of sphingomyelin (mole fraction (x) = 0.2), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (x = 0.7), 1, 2-dimyristoyl-sn-glycero-3-phospho-rac-glycerol (x = 0.1), and either the fluorescent sphingomyelin analog Bodipy-sphingomyelin or [(14)C]sphingomyelin as substrates. However, this activity was not present in either very low density lipoprotein or the high density lipoprotein subfractions HDL(2) and HDL(3). Oxidation of LDL abrogated its sphingomyelinase activity. Aggregation of the liposomes upon incubation with LDL was evident from the light scattering measurements. Microinjection of LDL to the surface of giant liposomes composed of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC), N-palmitoyl-d-sphingomyelin (C16:0-sphingomyelin), and Bodipy-sphingomyelin as a fluorescent tracer (0.75:- 0.20:0.05, respectively) revealed the induction of vectorial budding of vesicles, resembling endocytosis.     

Structural analysis of the specific capsular polysaccharide of Streptococcus pneumoniae type 45 (American type 72)

The specific capsular polysaccharide of Streptococcus pneumoniae type 45 (American type 72) was found to be a high molecular weight polymer composed of D-galactose, 2-acetamido-2-deoxy-D-galactose, 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2-deoxy-L-fucose, L-rhamnose, glycerol, and phosphate (2:1:1:1:1:1:1). Partial hydrolysis, dephosphorylation, methylation analysis, periodate oxidation studies, and one- and two-dimensional 1H and 13C high-field nuclear magnetic resonance experiments showed the polysaccharide to be a branched polymer of a 1-phosphoglycerol-substituted hexasaccharide repeating unit having the structure: (formula; see text).     

产有机酸采油菌的筛选及产酸情况的分析

目的:从大庆油田原油样品中筛选出2株产有机酸量较高的菌株,并对其产物进行分析.方法:根据形态特征、生理生化性质和16S rDNA序列分析对菌株进行鉴定,并运用GC/MS法对发酵液进行分析.结果:经鉴定这两株为枯草芽孢杆菌,菌株T10 -3的发酵液中含有乙酸11.407％,异丁酸9.375％,丁二醇79.217％;菌株DH -2 -l发酵液的中含有异丁酸41.56％,丁二醇46.619％,异戊酸4.138％,异庚酸10.680％.结论:这两株细菌在微生物采油方面均有良好的应用前景.     

(2-O-alpha-D-galactopyranosyl-4-O-methyl-alpha-D-glucurono)-D-xylan from Eucalyptus globulus Labill.

An unusual heteroxylan composed of galactosyl, 4-O-methyl-glucuronosyl and xylosyl residues with molar ratio 1:3:30 was isolated from the wood of Eucalyptus globulus Labill. The results of linkage analysis, supported by data of 1H, 2D 1H-1H COSY and 13C NMR spectroscopy, revealed that the polysaccharide is a (2-O-alpha-D-galactopyranosyl-4-O-methyl-alpha-D- glucurono)-D-xylan with a (1-->4)-linked beta-D-xylopyranosyl backbone branched at O-2 by short side chains composed of terminal 4-O-methyl-alpha-D-glucuronic acid and of 4-O-methyl-alpha-D-glucuronic acid substituted at O-2 with alpha-D-galactose.     

Chemical and apoptotic properties of hydroxy-ceramides containing long-chain bases with unusual alkyl chain lengths

We analysed four types of free ceramides (Cer 1, Cer 2, Cer 3 and Cer 4) from equine kidneys by electrospray ionization mass spectrometry. Cer 1 was composed of dihydroxy long-chain bases (dLCBs) of (4E)-sphingenine (d18:1), sphinganine and non-hydroxy fatty acids (NFAs); Cer 2 was composed of trihydroxy LCBs (tLCBs) of 4-hydroxysphinganine, t16:0, t18:0, t19:0 and t20:0, and NFAs; Cer 3 was composed of dLCBs, d16:1, d17:1, d18:1, d19:1 and d20:1, and hydroxy FAs (HFAs); and Cer 4 was composed of tLCBs, t16:0, t17:0, t18:0, t19:0 and t20:0, and HFAs. The results indicate all ceramide species containing LCBs with non-octadeca lengths (NOD-LCBs) can be classified into hydroxy-ceramides since these species always consist of tLCBs, and/or HFAs. Furthermore, such species tend to contain FAs with longer acyl chains but contain neither palmitate (C16:0) nor its hydroxylated form (C16:0h). The apoptosis-inducing activities of these hydroxyl-ceramides towards tumour cell lines were compared with that of non-hydroxy-ceramides, dLCB-NFA (Cer 1). Monohydroxy-ceramides, tLCB-NFA (Cer 2) and dLCB-HFA (Cer 3), exhibited stronger activities, whereas dihydroxy-ceramides, tLCB-HFA (Cer 4), exhibited similar or weaker activity than dLCB-NFA (Cer 1), depending on cell lines.     

Structural characterization of the antigenic O-polysaccharide in the lipopolysaccharide produced by Actinobacillus pleuropneumoniae serotype 14

The antigenic O-polysaccharide of the lipopolysaccharide produced by Actinobacillus pleuropneumoniae serotype 14 was shown by chemical analysis and 1D and 2D nuclear magnetic resonance methods to be a high-molecular-mass polymer of a repeating disaccharide unit composed of a chain of (1-->5)-linked beta-D-galactofuranose (beta-D-Galf) residues substituted at their O-2 positions by alpha-D-galactopyranose residues (D-Galp) (1:1): [formula: see text].     

Structural studies of the capsular polysaccharide from Haemophilus pleuropneumoniae serotype 1

The capsular polysaccharide of Haemophilus pleuropneumoniae serotype 1 (ATCC 27088) was found to be a teichoic acid type polysaccharide of a repeating disaccharide unit composed of 2-acetamido-2-deoxy-D-glucose and D-galactose units. By composition analysis, methylation, partial hydrolysis, dephosphorylation, and one- and two-dimensional 500-MHz proton nuclear magnetic resonance experiments, together with 13C nuclear magnetic resonance studies, it was concluded that the capsular polysaccharide is a high molecular weight linear polymer having the structure: (Formula: see text)     

Membrane composition determines pardaxin's mechanism of lipid bilayer disruption

Pardaxin is a membrane-lysing peptide originally isolated from the fish Pardachirus marmoratus. The effect of the carboxy-amide of pardaxin (P1a) on bilayers of varying composition was studied using (15)N and (31)P solid-state NMR of mechanically aligned samples and differential scanning calorimetry (DSC). (15)N NMR spectroscopy of [(15)N-Leu(19)]P1a found that the orientation of the peptide's C-terminal helix depends on membrane composition. It is located on the surface of lipid bilayers composed of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and is inserted in lipid bilayers composed of 1,2-dimyristoyl-phosphatidylcholine (DMPC). The former suggests a carpet mechanism for bilayer disruption whereas the latter is consistent with a barrel-stave mechanism. The (31)P chemical shift NMR spectra showed that the peptide significantly disrupts lipid bilayers composed solely of zwitterionic lipids, particularly bilayers composed of POPC, in agreement with a carpet mechanism. P1a caused the formation of an isotropic phase in 1-palmitoyl-2-oleoyl-phosphatidylethanolamine (POPE) lipid bilayers. This, combined with DSC data that found P1a reduced the fluid lamellar-to-inverted hexagonal phase transition temperature at very low concentrations (1:50,000), is interpreted as the formation of a cubic phase and not micellization of the membrane. Experiments exploring the effect of P1a on lipid bilayers composed of 4:1 POPC:cholesterol, 4:1 POPE:cholesterol, 3:1 POPC:1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG), and 3:1 POPE:POPG were also conducted, and the presence of anionic lipids or cholesterol was found to reduce the peptide's ability to disrupt bilayers. Considered together, these data demonstrate that the mechanism of P1a is dependent on membrane composition.     

Characterization of the lipopolysaccharide O-antigen of Cronobacter turicensis HPB3287 as a polysaccharide containing a 5,7-diacetamido-3,5,7,9-tetradeoxy-D-glycero-D-galacto-non-2-ulosonic acid (legionaminic acid) residue

Cronobacter turicensis, previously known as Enterobacter sakazakii, is a Gram-negative opportunistic food-borne pathogen that has been reported as a cause of life-threatening neonatal infections. From chemical and physical analyses involving composition analysis, methylation, two-dimensional high-resolution nuclear magnetic resonance, and mass spectrometry methods, the antigenic O-polysaccharide in the smooth-type lipopolysaccharide of C. turicensis (strain HPB 3287) was determined to be a high molecular mass polymer of a repeating pentasaccharide unit composed of D-galactose, D-glucose, 2-acetamido-2-deoxy-D-galactose, and 5,7-diacetamido-3,5,7,9-tetradeoxy-D-glycero-D-galacto-non-2-ulosonic acid (legionaminic acid), in a molar ratio 2:1:1:1, and having the structure: [see formula in text].     

Structural characterization of the lipopolysaccharide O-polysaccharide antigen produced by Flavobacterium columnare ATCC 43622.

The structure of the antigenic O-chain polysaccharide of Flavobacterium columnare ATCC 43622, a Gram-negative bacterium that causes columnaris disease in warm water fish, was determined by high-field 1D and 2D NMR techniques, MS, and chemical analyses. The O-chain was shown to be an unbranched linear polymer of a trisaccharide repeating unit composed of 2-acetamido-2-deoxy-d-glucuronic acid (d-GlcNAcA), 2-acetamidino-2,6-dideoxy-l-galactose (l-FucNAm) and 2-acetamido-2,6-dideoxy-d-xylo-hexos-4-ulose (d-Sug) (1 : 1 : 1), having the structure: [structure: see text].     

Crystal structure of a novel-type archaeal rubisco with pentagonal symmetry.

BACKGROUND: Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the key enzyme of the Calvin-Benson cycle and catalyzes the primary reaction of CO2 fixation in plants, algae, and bacteria. Rubiscos have been so far classified into two types. Type I is composed of eight large subunits (L subunits) and eight small subunits (S subunits) with tetragonal symmetry (L8S8), but type II is usually composed only of two L subunits (L2). Recently, some genuinely active Rubiscos of unknown physiological function have been reported from archaea. RESULTS: The crystal structure of Rubisco from the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1 (Tk-Rubisco) was determined at 2.8 A resolution. The enzyme is composed only of L subunits and showed a novel (L2)5 decameric structure. Compared to previously known type I enzymes, each L2 dimer is inclined approximately 16 degrees to form a toroid-shaped decamer with its unique L2-L2 interfaces. Differential scanning calorimetry (DSC), circular dichroism (CD), and gel permeation chromatography (GPC) showed that Tk-Rubisco maintains its secondary structure and decameric assembly even at high temperatures. CONCLUSIONS: The present study provides the first structure of an archaeal Rubisco, an unprecedented (L2)5 decamer. Biochemical studies indicate that Tk-Rubisco maintains its decameric structure at high temperatures. The structure is distinct from type I and type II Rubiscos and strongly supports that Tk-Rubisco should be classified as a novel type III Rubisco.     

Structure of the antigenic O-polysaccharide of the lipopolysaccharide produced by Salmonella eimsbuttel

The smooth lipopolysaccharide produced by Salmonella eimsbuttel, which had the O:6, O:7, and O:14 antigenic factors defined in the Kauffmann-White classification, was shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, composition analysis, methylation, periodate oxidation, deamination, and 1H and 13C nuclear magnetic resonance studies to contain a high molecular weight O-chain polysaccharide composed of D-mannose (four parts), D-glucose (one part), and 2-acetamido-2-deoxy-D-glucose (one part). It was a branched polymer of a repeating hexasaccharide unit having the structure (formula; see text).     

Nutritional balance of essential amino acids and carbohydrates of the adult worker honeybee depends on age

Dietary sources of essential amino acids (EAAs) are used for growth, somatic maintenance and reproduction. Eusocial insect workers such as honeybees are sterile, and unlike other animals, their nutritional needs should be largely dictated by somatic demands that arise from their role within the colony. Here, we investigated the extent to which the dietary requirements of adult worker honeybees for EAAs and carbohydrates are affected by behavioural caste using the Geometric Framework for nutrition. The nutritional optimum, or intake target (IT), was determined by confining cohorts of 20 young bees or foragers to liquid diets composed of specific proportions of EAAs and sucrose. The IT of young, queenless bees shifted from a proportion of EAAs-to-carbohydrates (EAA:C) of 1:50 towards 1:75 over a 2-week period, accompanied by a reduced lifespan on diets high in EAAs. Foragers required a diet high in carbohydrates (1:250) and also had low survival on diets high in EAA. Workers exposed to queen mandibular pheromone lived longer on diets high in EAA, even when those diets contained 5× their dietary requirements. Our data show that worker honeybees prioritize their intake of carbohydrates over dietary EAAs, even when overeating EAAs to obtain sufficient carbohydrates results in a shorter lifespan. Thus, our data demonstrate that even when young bees are not nursing brood and foragers are not flying, their nutritional needs shift towards a diet largely composed of carbohydrates when they make the transition from within-hive duties to foraging.     

Seasonal variations of biochemical, pigment, fatty acid, and sterol compositions in female Crassostrea corteziensis oysters in relation to the reproductive cycle

Wild female Crassostrea corteziensis oyster (n=245) were analyzed over one year to understand the main ecophysiological events associated to gonad development. Different indicators (mainly biochemical) were analyzed to infer: i) utilization and accumulation of energy reserves (e.g. neutral lipids, carbohydrates, proteins; vitellogenin), ii) membrane components provided by the diet as essential nutrients and indicative of cell proliferation (e.g. highly unsaturated fatty acids linked to phospholipids, sterols), iii) indicators of food availability (chlorophyll a in water, pigments in tissues, specific fatty acids and sterols), iv) gonad development (e.g. gonad coverage area, vitellin). A PCA analysis was applied to 269 measured variables. The first PC (PC1) was composed of total carbohydrate and lipid concentration, percentage of esterified sterols, fatty acids specific of diatoms; 16:1n-7/16:0, 20:5n-3 in neutral lipids with positive loadings and non methylene-interrupted fatty acids (NMI) in neutral lipids with negative loadings. The second PC (PC2) was composed of 18:4n-3 in lipid reserves and the concentration of zeaxanthin, a pigment typical of cyanobacteria with positive loadings and the proportion of 20:4n-6 in polar lipids with negative loading. The third PC (PC3) was composed of gonad coverage area (GCA) and the concentration of vitellin. Variation in GCA confirms that gonad development began in April with an extended period of spawning and rematuration from April to November. The PCA further shows that a second period of minimal maturation from November to March corresponds to the accumulation of reserves (PC1) together with an initial high availability of food (PC2) at the beginning of this period. These two periods are in accordance with the classical periods of allocation of energy to reserves followed by gonad development reported for several mollusks.     

Structural characterization of the antigenic capsular polysaccharide and lipopolysaccharide O-chain produced by Actinobacillus pleuropneumoniae serotype 15.

The specific capsular polysaccharide produced by Actinobacillus pleuropneumoniae serotype 15 was determined to be a high-molecular-mass polymer having [alpha]D + 69 degrees (water) and composed of a linear backbone of phosphate diester linked disaccharide units of 2-acetamido-2-deoxy-D-glucose (D-GlcNAc) and 2-acetamido-2-deoxy-D-galactose (D-GalNAc) residues (1:1). Thirty percent of the D-GalNAc residues were substituted at O-4 by beta-D-galactopyranose (beta-D-Galp) residues. Through the application of chemical and NMR methods, the capsule, which defines the serotype specificity of the bacterium, was found to have the structure [structure: see text]. The O-polysaccharide (O-PS) component of the A. pleuro pneumoniae serotype 15 lipopolysaccharide (LPS) was characterized as a linear unbranched polymer of repeating pentasaccharide units composed of D-glucose (2 parts) and D-galactose (3 parts), shown to have the structure [structure: see text]. The O-PS was chemically identical with the O-antigen previously identified in the LPSs produced by A. pleuro pneumoniae serotypes 3 and 8.     

Composition analysis and antioxidant activity of polysaccharide from Dendrobium denneanum

Three polysaccharide fractions (DDP1-1, DDP2-1 and DDP3-1) were successfully purified from the crude polysaccharide of Dendrobium denneanum by DEAE-Cellulose and Sephadex G-200 column chromatography. The average molecular weights (Mws) of these fractions were 51.5, 26.1 and 6.95 kDa, respectively. Monosaccharide components analysis indicated that DDP1-1 and DDP2-1 were composed of arabinose, xylose, mannose, glucose and galactose in a molar ratio of 1.00:2.82:57.11:140.82:7.76 and 1.00:1.62:1.18:77.5:7.79. DDP3-1 was composed of arabinose, mannose, glucose and galactose in a molar ratio of 1.00:1.03:8.84:2.00. On the basis of antioxidant test in vitro, DDP2-1 exhibited the highest antioxidant ability among these samples.     

Composition and antioxidant activity of the polysaccharides from cultivated Saussurea involucrata

Polysaccharides from cultivated Saussurea involucrata (CSIP) were purified, two major fractions (CSIP1-2 and CSIP2-3) were investigated for their molecular weights, monosaccharide compositions and in vitro antioxidant activities. The results suggested that the molecular weights of CSIP1-2 and CSIP2-3 were approximately 163.5 kDa and 88.6 kDa, respectively. CSIP1-2 was composed of glucose, galactose, xylose, rhamnose, arabinose and galacturonic acid with a molar ratio of 1.651:0.39:0.062:8.331:1.759:40.426. CSIP2-3 was composed of glucose, galactose, xylose, rhamnose, arabinose and galacturonic acid with a molar ratio of 0.762:0.657:0.112:5.587:0.318:44.655. Different scavenging activities on superoxide radical, DPPH radical and hydroxyl radical were observed in CSIP1-2 and CSIP2-3 at tested concentrations.