Nuclear Magnetic Resonance Spectral Analysis Research Articles

A facile synthesis and application of ethyl 6-(bromomethyl)-[1,3]dioxolo[4,5-g]quinoline-7-carboxylate

Visible-light-induced radical bromination of ethyl 6-methyl-[1,3]dioxolo[4,5-g]quinoline-7-carboxylate (1) was effectively conducted with N-bromosuccinimide using a 150-W tungsten bulb as an initiator, leading to the desired monobromo product ethyl 6-(bromomethyl)-[1,3]dioxolo[4,5-g]quinoline-7-carboxylate (2) in good yield of 76 %. Using the present procedure, a 46 % improvement in yield of 2 was achieved when compared with the previous method used by us. In addition, the trace amount of byproduct was isolated and identified as ethyl 9-bromo-6-methyl-[1,3]dioxolo[4,5-g]quinoline-7-carboxylate (3) based on 1H nuclear magnetic resonance (NMR) spectral analysis. As an extended application of 2, a new synthesis of symmetrical 2-quinolylmethoxyphenyl-containing diethers 11a–c was achieved via Williamson reaction with some dihydroxy arenes (10a–c).

Synthesis, crystal growth and spectroscopic investigation of novel metal organic crystal: β-Alanine cadmium bromide monohydrate (β-ACBM)

β-Alanine cadmium bromide monohydrate (β-ACBM), a new metal organic crystal has been grown from aqueous solution by slow evaporation technique. The grown crystals have been subjected to single crystal X-ray diffraction analysis to determine the crystal structure. The β-ACBM crystallized in monoclinic system with space group P21/c. The presence of protons and carbons in the β-alanine cadmium bromide monohydrate was confirmed by 1H and 13C nuclear magnetic resonance spectral analysis. The mode of vibration of different molecular groups present in β-ACBM was identified by FT-IR spectral analysis. Transparency of crystals in UV–Vis–NIR region has also been studied. The thermal characteristics of as-grown crystals were analyzed using thermo gravimetric and differential thermal analyses. The magnetic property of the grown crystal was investigated using Vibrating Sample Magnetometer (VSM) at ambient temperature. The mechanical stability of β-ACBM was evaluated by Vickers microhardness measurement.

Isolation and HPLC method development of azafrin from Alectra parasitica var. chitrakutensis

This study was undertaken to isolate and quantify azafrin in Alectra parasitica (Scrophulariaceae) rhizomes. A simple method for the isolation of carotenoid, azafrin, involves solvent extraction of the dried rhizome powder using a single solvent and further purification by recrystallisation. The structure of the compound was elucidated and confirmed by thin-layer chromatography, infrared spectroscopy, mass spectroscopy and nuclear magnetic resonance spectral analysis. A specific and rapid reversed-phase high-performance liquid chromatography (HPLC) method was developed for the analysis of azafrin. The method was validated for accuracy, precision, linearity and specificity. Validation revealed that the method is specific, accurate, precise, reliable and reproducible. The proposed HPLC method can be used for the identification and quantitative analysis of azafrin in A. parasitica rhizomes.

4β-Hydroxywithanolide E isolated from Physalis pruinosa calyx decreases inflammatory responses by inhibiting the NF-κB signaling in diabetic mouse adipose tissue

Chronic inflammation in adipose tissue together with obesity induces insulin resistance. Inhibitors of chronic inflammation in adipose tissue can be a potent candidate for the treatment of diabetes; however, only a few compounds have been discovered so far. The objective of this study was to find a novel inhibitor that can suppress the inflammatory response in adipose tissue and to elucidate the intracellular signaling mechanisms of the compound. To find the active compounds, we established an assay system to evaluate the inhibition of induced MCP-1 production in adipocyte/macrophage coculture in a plant extract library. The active compound was isolated by performing high-performance liquid chromatography (HPLC) and was determined as 4β-hydroxywithanolide E (4βHWE) by nuclear magnetic resonance (NMR) and mass spectroscopy (MS) spectral analyses. The effect of 4βHWE on inflammation in adipose tissue was assessed with adipocyte culture and db/db mice. During the screening process, Physalis pruinosa calyx extract was found to inhibit production of MCP-1 in coculture strongly. 4βHWE belongs to the withanolide family of compounds, and it has the strongest MCP-1 production inhibitory effect and lowest toxicity than any other withanolides in coculture. Its anti-inflammatory effect was partially dependent on the attenuation of NF-κB signaling in adipocyte. Moreover, in vivo experiments showed that the oral administration of 4βHWE to db/db mice resulted in the inhibition of macrophage invasion and cytokine expression in adipose tissue after 2 weeks of treatment; improved the plasma adiponectin, non-esterified fatty acids and MCP-1 concentrations; and increased glucose tolerance after 3 to 4 weeks of treatment. These results suggest that 4βHWE has anti-inflammatory effect via inhibition of NF-κB activation in adipocyte. Moreover, the attenuation of inflammation in adipocyte has an effect on the inhibition of macrophage accumulation in obese adipose tissue. Consequently, 4βHWE improves impaired glucose tolerance. Thus, 4βHWE is a useful natural anti-inflammatory compound to attenuate progression of diabetes and obesity.

Preparation and characterization of biopolymers comprising chitosan-grafted-ENR via acid-induced reaction of ENR50 with chitosan

This paper describes the first detailed tailored-approach for the preparation of biopolymers comprising chitosan (CTS) grafted onto the backbone of epoxidized natural rubber (CTS-g-ENR). In a typical experiment, appropriate amount of CTS and AlCl3·6H2O was added to a specified amount of ENR50 (ENR with about 50% epoxy content) dissolved in a dual-solvent consisting of 1,4-dioxane and water (97.5:2.5% v/v) and the resulting mixture refluxed with continuous stir- ring for 6 hours. Nuclear magnetic resonance (NMR) spectral analysis of a biocomposite, CTS-g-ENR-P1, revealed that its epoxy content is 22.36% which is considerably lower than 44.93% as determined for ENR50-control (ENR50 derivative obtained under similar experimental condition but in the absence of CTS). This means that the grafting of CTS onto the backbone of ENR had occurred. The revelation is affirmed by the presence of the characteristic absorption bands of CTS and ENR, and the appearance of new bands at 1219, 902 and 733 cm -1 in the Fourier transform infrared (FTIR) spectrum of CTS-g-ENR-P1. Further evidence that CTS had been successfully grafted onto the backbone of ENR can be deduced and described in this paper from the data obtained by means of Differential Scanning Calorimetric analysis, Thermogravimetric analysis and Variable Pressure Scanning Electron Microscopy.

Synthesis and Characterization of Ethylene‐Bridged Copolycarbosilazane as Precursors for Silicon Carbonitride Ceramics

An ethylene‐bridged copolycarbosilazane precursor of copolysilylethylenediamine (co‐PSDA) is synthesized by polycondensation of ethylenediamine with the mixture of vinylmethyldichlorosilane and methyldichlorosilane in the presence of triethylamine as acid absorbing agent. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR, 1H NMR and 13C NMR) spectral analysis of the as‐synthesized co‐PSDA suggests a structure of ethylene‐bridged polycarbosilazane having –Si–N–C–C–N– as backbone chain with –CH=CH2, –H and –CH3 attached to Si as side groups. Co‐PSDA can be cross‐linked at 80°C using 2, 2‐azobisisobutyronitrile as initiator through the polyaddition of the vinyl group and dehydrogenation/deamination of Si–H and N–H. Then the cross‐linked co‐PSDA precursor is pyrolyzed at 1000°C in argon, giving out amorphous silicon carbon nitride (SiCN) ceramics with a high ceramic yield of 76 wt%. The obtained SiCN ceramics consist of nitrogen‐rich silicon sites of SiN4 as predominant component and some SiCN3 sites, which should arise from the breaking of N–C bonds below 600°C and the formation of active N–Si bonds.

Meleagrin, a New FabI Inhibitor from Penicillium chryosogenum with at Least One Additional Mode of Action

Bacterial enoyl-acyl carrier protein reductase (FabI) is a promising novel antibacterial target. We isolated a new class of FabI inhibitor from Penicillium chrysogenum, which produces various antibiotics, the mechanisms of some of them are unknown. The isolated FabI inhibitor was determined to be meleagrin by mass spectroscopy and nuclear magnetic resonance spectral analyses, and its more active and inactive derivatives were chemically prepared. Consistent with their selective inhibition of Staphylococcus aureus FabI, meleagrin and its more active derivatives directly bound to S. aureus FabI in a fluorescence quenching assay, inhibited intracellular fatty acid biosynthesis and growth of S. aureus, and increased the minimum inhibitory concentration for fabI-overexpressing S. aureus. The compounds that were not effective against the FabK isoform, however, inhibited the growth of Streptococcus pneumoniae that contained only the FabK isoform. Additionally no resistant mutant to the compounds was obtained. Importantly, fabK-overexpressing Escherichia coli was not resistant to these compounds, but was resistant to triclosan. These results demonstrate that the compounds inhibited another target in addition to FabI. Thus, meleagrin is a new class of FabI inhibitor with at least one additional mode of action that could have potential for treating multidrug-resistant bacteria.

무 시들음병균이 생산하는 Phytotoxin의 병원성 및 저항성에서 역할

무 시들음병에 대한 저항성 검정 체계를 확립하기 위하여 실험하는 과정에서 병원균인 Fusarium oxysporum f. sp. raphani가 무 유묘에 독성(phytotoxicity)을 일으키는 독소(phytotoxin)를 생산한다는 것을 발견했다. F. oxysporum f. sp. raphani KR1 균주는 여러 배지 중 malt extract broth 배지에서 배양하였을 때 그리고 <TEX>$25^{\circ}C$</TEX>에서 14일 동안 150rpm으로 진탕배양하였을 때 가장 많은 독소를 생산하였다. 무에 대한 독성 반응을 이용하여 F. oxysporum f. sp. raphani의 배양액으로부터 phytotoxin을 분리하였다. 그리고 Mass와 NMR Spectroscopy 분석을 통하여 이 화합물은 fusaric acid로 동정되었다. 독소의 역할을 규명하기 위하여 fusaric acid를 무, 양배추, 브로콜리 등 F. oxysporum f. sp. raphani의 기주 및 비기주 배추과 작물에 대한 독소 활성을 조사하였다. Fusaric aicd는 무 유묘에 대하여 농도 의존적으로 활성을 보였으며, F. oxysporum f. sp. raphani에 대한 감수성 품종뿐만 아니라 저항성 품종에 대해서도 유사한 정도의 독성을 나타냈다. 그리고 F. oxysporum f. sp. raphani가 생산하는 fusaric acid는 병원균의 비기주 배추과 작물인 양배추와 브로콜리에 대해서도 강한 활성을 보였다. 따라서 이들 결과는 이 독소가 병원성 관련 독소이나 비기주 특이적 독소이며, 무 시들음병 저항성 검정에서 이 독소가 제거된 포자현탁액을 접종원으로 사용해야 한다는 것을 나타낸다. In the course of a developing screening method for resistant radish to Fusarium oxysporum f. sp. raphani, we found that the fungus produces phytotoxic compound against Raphanus sativus. The culture filtrate of F. oxysporum f. sp. raphani KR1 represented the strongest phytotoxicity when the fungus was incubated in the malt extract broth with 150 rpm at <TEX>$25^{\circ}C$</TEX> for 14 days. Under bioassay-guided purification, we isolated a substance from liquid culture of F. oxysporum f. sp. raphani KR1, with phytotoxic effect against R. sativus. The compound was identified as fusaric acid by mass and nuclear magnetic resonance spectral analyses. Phytotoxicity of the compound against cruciferous vegetable crops, including radish, cabbage, and broccoli, was investigated. Fusaric acid represented phytotoxicity on radish seedlings by concentration dependant manner. And the phytotoxin demonstrated strong phytotoxicity on the resistant cultivars as well as susceptible cultivars of radish to F. oxysporum f. sp. raphani. In addition, fusaric acid isolated from the fungus also showed a potent phytotoxic efficacy against non-host Brassicaceae crops of the fungus such as cabbage and broccoli. The results demonstrate that fusaric acid produced by F. oxysporum f. sp. raphani is non-host-specific toxin and for screening of resistant radish to the fungal pathogen, spore suspension of the fungus without the phytotoxin has to be used.

Novel monosaccharide fermentation products in Caldicellulosiruptor saccharolyticus identified using NMR spectroscopy

BackgroundCaldicellulosiruptor saccharolyticus is a thermophilic, Gram-positive, non-spore forming, strictly anaerobic bacterium of interest in potential industrial applications, including the production of biofuels such as hydrogen or ethanol from lignocellulosic biomass through fermentation. High-resolution, solution-state nuclear magnetic resonance (NMR) spectroscopy is a useful method for the identification and quantification of metabolites that result from growth on different substrates. NMR allows facile resolution of isomeric (identical mass) constituents and does not destroy the sample.ResultsProfiles of metabolites produced by the thermophilic cellulose-degrading bacterium Caldicellulosiruptor saccharolyticus DSM 8903 strain following growth on different monosaccharides (D-glucose, D-mannose, L-arabinose, D-arabinose, D-xylose, L-fucose, and D-fucose) as carbon sources revealed several unexpected fermentation products, suggesting novel metabolic capacities and unexplored metabolic pathways in this organism. Both 1H and 13C nuclear magnetic resonance (NMR) spectroscopy were used to determine intracellular and extracellular metabolite profiles. One dimensional 1H NMR spectral analysis was performed by curve fitting against spectral libraries provided in the Chenomx software; 2-D homonuclear and heteronuclear NMR experiments were conducted to further reduce uncertainties due to unassigned, overlapping, or poorly-resolved peaks. In addition to expected metabolites such as acetate, lactate, glycerol, and ethanol, several novel fermentation products were identified: ethylene glycol (from growth on D-arabinose), acetoin and 2,3-butanediol (from growth on D-glucose, L-arabinose, and D-xylose), and hydroxyacetone (from growth on D-mannose, L-arabinose, and D-xylose). Production of ethylene glycol from D-arabinose was particularly notable, with around 10% of the substrate carbon converted into this uncommon fermentation product.ConclusionsThe present research shows that C. saccharolyticus, already of substantial interest due to its capability for biological ethanol and hydrogen production, has further metabolic potential for production of higher molecular weight compounds, such as acetoin and 2,3-butanediol, as well as hydroxyacetone and the uncommon fermentation product ethylene glycol. In addition, application of nuclear magnetic resonance (NMR) spectroscopy facilitates identification of novel metabolites, which is instrumental for production of desirable bioproducts from biomass through microbial fermentation.

Correspondence of Fatty Acid and Drug Binding Sites on Human Serum Albumin: A Two-Dimensional Nuclear Magnetic Resonance Study

The ability of human serum albumin (HSA) to bind fatty acids (FA) in multiple sites has been revealed by many studies. Here we detect and characterize nine individual binding sites by two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy of 18-[(13)C]-oleic acid (OA) complexed with HSA. We characterize site-specific FA binding by addition of (i) different FA molar ratios (from 1:1 to 4:1 OA:HSA) to observe the order of filling and occupancy of binding sites; (ii) methyl-β-cyclodextrin, as a FA acceptor, to observe the dissociation of FA; and (iii) drugs (with known binding sites in the crystal structure) to reveal the correspondence of three NMR peaks with sites in the crystal structure. At 1:1 and 2:1 OA:HSA ratios, three sites were shown to fill sequentially. These high-affinity sites were well resolved from additional sites (one medium-affinity and five low-affinity) observed at 3:1 and 4:1 OA:HSA ratios. Methyl-β-cyclodextrin extracted OA from individual sites in the reverse order of filling. FA bound in three low-affinity sites were displaced by drugs shown to bind in crystalline HSA to FA sites 7 and 3 (Sudlow's drug sites I and II, respectively) and FA site 6. With this strategy, 2D NMR spectral analysis permits site-specific characterization of the binding of drugs and FA and provides a sensitive probe of the mutual effects of FA and ligand binding.

Self-Assembly and UV-Curing Property of Polymerized Lyotropic Liquid Crystal Monomer of Sodium 3,4,5-tris(11-acryloxyundecyloxy)benzoate

A polymerized lyotropic liquid crystal monomer of sodium 3,4,5-tris(11-acryloxyundecyloxy)-benzoate was synthesized by a convenient route starting from 3,4,5-trihydroxybenzoic acid via esterification followed by etherification, acylation and finally neutralization. The chemical structure was confirmed by Fourier transform infrared (FT-IR) and H1 nuclear magnetic resonance spectral analysis. The self-organization behavior of the monomer with deionized water in methanol at room temperature was also demonstrated. The assemblies were characterized by polarized optical microscope and X-ray diffraction. The results show that a solution containing 80:20 of the monomer to water was found to be able to self-organize into Lamellar (La) phase and 92:8 with inverted hexagonal (HII) phase, which was in accordance with the theoretical calculation of critical packing parameter. It suggests that the concentration of the monomer was the key factor to influence assembly structure. Additionally, the acrylate conversion with different photoinitiators and nanostructure retention after polymerization were investigated. The research shows that the acrylate conversion of the monomer with Darocur2959 could reach up to 78% when irradiated by 30 mW/cm2 UV light of 365 nm for 30 min characterized by Real-time FT-IR as well as the sol-gel method. Meanwhile, the La and HII phase nanostructures were both retained after polymerization.

The smell of moulting:N-acetylglucosamino-1,5-lactone is a premoult biomarker and candidate component of the courtship pheromone in the urine of the blue crab,Callinectes sapidus

Female blue crabs (Callinectes sapidus) in their pubertal moult stage release unidentified sex pheromone molecules in their urine, causing males to respond with courtship behaviours including a display called courtship stationary paddling and a form of precopulatory guarding called cradle carry. We hypothesized that pheromones are mixtures of molecules and are more concentrated in urine of pubertal premoult females compared with other moulting stages and thus that these molecules are biomarkers (i.e. metabolites that can be used as an indicator of some biological state or condition) of pubertal premoult females. We tested this hypothesis by combining bioassay-guided fractionation and biomarker targeting. To evaluate the molecular mass of the putative pheromone by bioassay-guided fractionation, we separated urine from pubertal premoult females and intermoult males by ultrafiltration into three molecular mass fractions. The <500 Da fraction and the 500-1000 Da fraction but not the >1000 Da fraction of female urine induced male courtship stationary paddling, but none of the fractions of male urine did. Thus, female urine contains molecules of <1000 Da that stimulate courtship behaviours in males. Biomarker targeting using nuclear magnetic resonance (NMR) spectral analysis of the 500-1000 Da fraction of urine from premoult and postmoult males and females revealed a premoult biomarker. Purification, nuclear magnetic resonance, mass spectrometry and high pressure liquid chromatography analysis of this premoult biomarker identified it as N-acetylglucosamino-1,5-lactone (NAGL) and showed that it is more abundant in urine of premoult females and males than in urine of either postmoult or juvenile females and males. NAGL has not been reported before as a natural product or as a molecule of the chitin metabolic pathway. Physiological and behavioural experiments demonstrated that blue crabs can detect NAGL through their olfactory pathway. Thus, we hypothesize that NAGL is a component of the sex pheromone and that it acts in conjunction with other yet unidentified components.

Calcium Selectivity in Liquid Membrane Transport using Anthraquinone Derived Redox Switched Synthetic Ionophores

Selective recognition of alkali and alkaline earth metal ion pairs viz.Li+, Na+, K+, Mg2+ and Ca2+ is of great biological importance. Design and synthesis of ionophores and receptor molecules capable of selectively binding and transporting substrates (neutral and ionic) are based on molecular recognition and used to develop membrane separation systems. This has potential applications in analytical, environmental, and biomimetic chemistry. We have designed and synthesized new series of anthraquinone derived single and double armed ionophores. Supermolecules have been isolated with these synthetic podands as host and metal ions as guest. Interaction has been confirmed by melting point (m.p.), infrared red (IR), and proton nuclear magnetic resonance (1H NMR) spectral analysis and cyclic voltammetric studies. Further, the liquid liquid extraction, bulk liquid membrane (BLM) transport, and supported liquid membrane (SLM) transport studies using polytetrafloroethylene membrane, cellulose nitrate membrane, onion membrane and egg shell membrane, have been done to find out the selectivity of these ionophores for various metal ions. Among the two liquid membrane systems used SLMs is more efficient than BLMs. It is found that double armed and bridged ionophores (A3 to A8) show better extraction ability than single armed ionophores (A1, A2) and ionophore A3 is calcium selective.

Antioxidative and cytoprotective effects of andrographolide against CCl4-induced hepatotoxicity in HepG2 cells

This article describes antioxidative and cytoprotective property of andrographolide, a major active component of the plant Andrographis paniculata (A. paniculata). High yields (2.7%) of andrographolide was isolated from the aerial parts of this plant via silica column chromatography. The purity of the compound was determined by high-performance thin-layer chromatography (HPTLC) and reversed phase high-performance liquid chromatography (HPLC) analysis. The structure was elucidated using techniques such as UV-visible spectrophotometry, elemental analysis, Fourier transform infrared (FT-IR), (1)H nuclear magnetic resonance ((1)H NMR), (13)C nuclear magnetic resonance ((13)C NMR) and mass spectral analysis and the data obtained were comparable with reported results. It was observed that andrographolide exhibited significant antioxidative property (IC50 = 3.2 µg/ml) by its ability to scavenge a stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) as compared to known antioxidants like ascorbic acid, butylated hydroxy toluene (BHT) and the plant extract. The cytoprotective role of andrographolide against carbon tetrachloride (CCl4) toxicity in human hepatoma HepG2 cell line was assessed using trypan blue exclusion test, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, by estimation of various leakage enzymes and by measuring the glutathione levels. The recovery obtained for andrographolide treatment in the presence of CCl4 was two-fold compared to A. paniculata extract for all other related biochemical parameters investigated. The results of the study indicate that andrographolide is a potent inhibitor of CCl4-mediated lipid peroxidation.

New generation of 1H NMR fingerprints for rapid identification of natural products

Nuclear Magnetic Resonance (NMR) spectroscopy is a highly versatile technique for structural elucidation in natural product research. However, its implementation as the ultimate identity test requires the accurate determination of the position and multiplicity of each proton resonance of the compound(s) of interest. In this report, quantitative 1H NMR (qHNMR) and computer-aided spectral analysis are combined to develop an efficient methodology for the complete analysis of 1H NMR signal patterns. This approach, termed 1 H iterative Full Spin Analysis (HiFSA), enables the production of detailed, reproducible 1H NMR profiles, i.e., 1H NMR fingerprints. These high resolution, field independent fingerprints can be used to unambiguously identify natural products in a wide variety of samples, including reference materials, enriched fractions, and crude extracts. Furthermore, they also provide a solid starting point for the characterization of structurally related unknown compounds. Illustrative examples of 1H NMR fingerprints of natural products and their generation by HiFSA will be presented.

Microbial transformation of maslinic acid by Cunninghamella blakesleana

The pentacyclic triterpenoid maslinic acid (1) was bioconverted by Cunninghamella blakesleana CGMCC 3.910, four metabolites were obtained. On the basis of nuclear magnetic resonance and high-resolution mass spectral analyses, their structures were identified as 2α,3β,7β-trihydroxyolean-12-en-28-oic acid (2), 2α,3β,15α-trihydroxyolean-12-en-28-oic acid (3), 2α,3β,7β,15α-tetrahydroxyolean-12-en-28-oic acid (4), 2α,3β,7β,13β-tetrahydroxyolean-11-en-28-oic acid (5), all of the metabolites were new compounds. The metabolic pathway was also investigated. This was the first report on the biotransformation of maslinic acid.

Production, Purification, and Characterization of Antifungal Metabolite from Pseudomonas aeruginosa SD12, a New Strain Obtained from Tannery Waste Polluted Soil

A new strain, SD12, was isolated from tannery waste polluted soil and identified as Pseudomonas aeruginosa on the basis of phenotypic traits and by comparison of 16S rRNA sequences. This bacterium exhibited broad-spectrum antagonistic activity against phytopathogenic fungi. The strain produced phosphatases, cellulases, proteases, pectinases, and HCN and also retained its ability to produce hydroxamate-type siderophore. A bioactive metabolite was isolated from P. aeruginosa SD12 and was characterized as 1-hydroxyphenazine ((1-OH-PHZ) by nuclear magnetic resonance (NMR) spectral analysis. The strain was used as a biocontrol agent against root rot and wilt disease of pyrethrum caused by Rhizoctonia solani. The stain is also reported to increase the growth and biomass of Plantago ovata. The purified compound, 1-hydroxyphenazine, also showed broad-spectrum antagonistic activity towards a range of phytopathogenic fungi, which is the first report of its kind.

Statistical approach for solid-state NMR spectra of cellulose derived from a series of variable parameters

Principle component analysis (PCA) was used to extract components from the solid-state nuclear magnetic resonance (NMR) spectra of bacterial cellulose (BC). Polymers such as cellulose have several domain structures, and their structure and dynamics are reflected in the variety of solid-state spectra derived from different parameters. The complexity of the obtained spectra makes the analysis of spectra from relaxation measurements difficult. Multivariate analysis, such as PCA, has been suggested as an option to improve NMR spectral analyses. In this study, we attempted to extract peak components from cross polarization (CP) experiment data from the variable contact time spectra of BC by using PCA. The extracted peaks were annotated according to previous reports, and the existence of crystalline Iα was clearly recognized. The important components of the BC structure (that is, crystalline Iα, amorphous form and mobility) were separated in the PCA-loading plot and CP curve. A multivariate analysis was used to extract components in solid-state nuclear magnetic resonance (NMR) spectra from bacterial cellulose (BC). Polymers such as cellulose have several domain structures, and their structure and dynamics are reflected in the variety of solid-state spectra derived from different parameters. Multivariate analysis, such as principle component analysis (PCA), is suggested as an option to improve analyses of complex NMR spectra from relaxation measurements. In this study we demonstrate the extraction of peak components using PCA from cross polarization experiment data with variable contact time spectra of BC.

Sulfamate proton solvent exchange in heparin oligosaccharides: Evidence for a persistent hydrogen bond in the antithrombin-binding pentasaccharide Arixtra

Sulfamate groups (NHSO(3)(-)) are important structural elements in the glycosaminoglycans (GAGs) heparin and heparan sulfate (HS). In this work, proton nuclear magnetic resonance (NMR) line-shape analysis is used to explore the solvent exchange properties of the sulfamate NH groups within heparin-related mono-, di-, tetra- and pentasaccharides as a function of pH and temperature. The results of these experiments identified a persistent hydrogen bond within the Arixtra (fondaparinux sodium) pentasaccharide between the internal glucosamine sulfamate NH and the adjacent 3-O-sulfo group. This discovery provides new insights into the solution structure of the Arixtra pentasaccharide and suggests that 3-O-sulfation of the heparin N-sulfoglucosamine (GlcNS) residues pre-organize the secondary structure in a way that facilitates binding to antithrombin-III. NMR studies of the GlcNS NH groups can provide important information about heparin structure complementary to that available from NMR spectral analysis of the carbon-bound protons.

The Structure of the XPF-ssDNA Complex Underscores the Distinct Roles of the XPF and ERCC1 Helix- Hairpin-Helix Domains in ss/ds DNA Recognition

Human XPF/ERCC1 is a structure-specific DNA endonuclease that nicks the damaged DNA strand at the 5' end during nucleotide excision repair. We determined the structure of the complex of the C-terminal domain of XPF with 10 nt ssDNA. A positively charged region within the second helix of the first HhH motif contacts the ssDNA phosphate backbone. One guanine base is flipped out of register and positioned in a pocket contacting residues from both HhH motifs of XPF. Comparison to other HhH-containing proteins indicates a one-residue deletion in the second HhH motif of XPF that has altered the hairpin conformation, thereby permitting ssDNA interactions. Previous nuclear magnetic resonance studies showed that ERCC1 in the XPF-ERCC1 heterodimer can bind dsDNA. Combining the two observations gives a model that underscores the asymmetry of the human XPF/ERCC1 heterodimer in binding at an ss/ds DNA junction.