Oxidative stress-induced metabolic changes in mouse C2C12 myotubes studied with high-resolution 13C, 1H, and 31P NMR spectroscopy

In this study, stress in relation to slaughter was investigated in a model system by the use of (13)C, (1)H, and (31)P nuclear magnetic resonance (NMR) spectroscopy for elucidating changes in the metabolites in C2C12 myotubes exposed to H(2)O(2)-induced stress. Oxidative stress resulted in lower levels of several metabolites, mainly amino acids; however, higher levels of alanine were apparent in the (13)C spectra after incubation with [(13)C(1)]glucose. In the (13)C spectra [(13)C(3)]lactate tended to increase after exposure to increasing concentrations of H(2)O(2); conversely, a tendency to lower levels of the unlabeled ((12)C) lactate were identified in the (1)H spectra after stress exposure. These data indicate an increase in de novo synthesis of alanine, concomitant with a release of lactate from the myotubes to the medium at oxidative stress conditions. The changes in the metabolite levels could possibly be useful as markers for meat quality traits.

Improved characterization of nod factors and genetically based variation in LysM Receptor domains identify amino acids expendable for nod factor recognition in Lotus spp

Formation of functional nodules is a complex process depending on host-microsymbiont compatibility in all developmental stages. This report uses the contrasting symbiotic phenotypes of Lotus japonicus and L. pedunculatus, inoculated with Mesorhizobium loti or the Bradyrhizobium sp. (Lotus), to investigate the role of Nod factor structure and Nod factor receptors (NFR) for rhizobial recognition, infection thread progression, and bacterial persistence within nodule cells. A key contribution was the use of 800 MHz nuclear magnetic resonance spectroscopy and ultrahigh-performance liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry for Nod factor analysis. The Nod factor decorations at the nonreducing end differ between Bradyrhizobium sp. (Lotus) and M. loti, and the NFR1/NFR5 extracellular regions of L. pedunculatus and L. japonicus were found to vary in amino acid composition. Genetic transformation experiments using chimeric and wild-type receptors showed that both receptor variants recognize the structurally different Nod factors but the later symbiotic phenotype remained unchanged. These results highlight the importance of additional checkpoints during nitrogen-fixing symbiosis and define several amino acids in the LysM domains as expendable for perception of the two differentially carbamoylated Nod factors.

Nuclear magnetic resonance-based metabonomics reveals strong sex effect on plasma metabolism in 17-year-old Scandinavians and correlation to retrospective infant plasma parameters

Nuclear magnetic resonance (NMR)-based metabonomics was carried out on plasma samples from a total of seventy-five 17-year-old Danes to investigate the impact of key parameters such as sex, height, weight, and body mass index on the plasma metabolite profile in a normal, healthy population. Principal component analysis identified sex to have a large impact on the NMR plasma metabolome, whereas no apparent effects of height, weight, and body mass index were found. Partial least square regression discriminant analysis and quantification of relative metabolite concentrations by integration of NMR signals revealed that the sex effect included differences in plasma lipoproteins (mainly high-density lipoprotein), glucose, choline, and amino acid content. Accordingly, the present study suggests a higher lipid synthesis in young women than young men and a higher protein turnover in young men compared with women. Data on plasma content of triglyceride, lipoprotein fractions, and cholesterol at an age of 9 months were available for selected individuals (n = 40); and partial least square regressions revealed correlations between these infant parameters and the NMR plasma metabolome at an age of 17 years. In conclusion, the present study demonstrates the feasibility of NMR-based metabonomics for obtaining a deeper insight into interindividual differences in metabolism and for exploring relationships between parameters measured early in life and metabolic status at a later stage.

Cloning and comparison of phylogenetically related chitinases from Listeria monocytogenes EGD and Enterococcus faecalis V583

AIMS

To compare enzymatic activities of two related chitinases, ChiA and EF0361, encoded by Listeria monocytogenes and Enterococcus faecalis, respectively.

METHODS AND RESULTS

The chiA and EF0361 genes were amplified by PCR, cloned and expressed with histidine tags, allowing easy purification of the gene products. ChiA had a molecular weight as predicted from the amino acid sequence, whereas EF0361 was 1840 Da lower than expected because of C-terminal truncation. The ChiA and EF0361 enzymes showed activity towards 4-nitrophenyl N,N'-diacetyl-beta-D-chitobioside with K(m) values of 1.6 and 2.1 mmol l(-1), respectively, and k(cat) values of 21.6 and 6.5 s(-1). The enzymes also showed activity towards 4-nitrophenyl beta-D-N, N', N''-triacetylchitotriose and carboxy-methyl-chitin-Remazol Brilliant Violet but not towards 4-nitrophenyl N-acetyl-beta-D-glucosaminide. Chitinolytic specificities of the enzymes were supported by their inactivity towards the substrates 4-nitrophenyl beta-D-cellobioside and peptidoglycan. The pH and temperature profiles for catalytic activities were relatively similar for both the enzymes.

CONCLUSION

The ChiA and EF0361 enzymes show a high degree of similarity in their catalytic activities although their hosts share environmental preferences only to some extent.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study contributes to an understanding of the chitinolytic activities by L. monocytogenes and Ent. faecalis. Detailed information on their chitinolytic systems will help define potential reservoirs in the natural environment and possible transmission routes into food-manufacturing plants.

Structural characterization of the acid-degraded secondary cell wall polymer of Geobacillus stearothermophilus PV72/p2

The secondary cell wall polymer (SCWP) from Geobacillus stearothermophilus PV72/p2, which is involved in the anchoring of the surface-layer protein to the bacterial cell wall layer, is composed of 2-amino-2-deoxy- and 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2-deoxy-D-mannose, and 2-acetamido-2-deoxy-D-mannuronic acid. The primary structure of the acid-degraded polysaccharide--liberated by HF-treatment from the cell wall--was determined by high-field NMR spectroscopy and mass spectrometry using N-acetylated and hydrolyzed polysaccharide derivatives as well as Smith-degradation. The polysaccharide was shown to consist of a tetrasaccharide repeating unit containing a pyruvic acid acetal at a side-chain 2-acetamido-2-deoxy-alpha-D-mannopyranosyl residue. Substoichiometric substitutions of the repeating unit were observed concerning the degree of N-acetylation of glucosamine residues and the presence of side-chain linked 2-acetamido-2-deoxy-beta-D-glucopyranosyl units: [Formula: see text].

Effect of magnetic field strength on NMR-based metabonomic human urine data. Comparative study of 250, 400, 500, and 800 MHz

Metabonomic analysis of urine utilizing high-resolution NMR spectroscopy and chemometric techniques has proven valuable in characterizing the biochemical response to an intervention. To assess the effect of magnetic field strength on information contained in NMR-based metabonomic data sets, 1H NMR spectra were acquired on 250-, 400-, 500-, and 800-MHz instruments, respectively, on the same set of human urine samples collected before and after dietary interventions with milk and with meat proteins. Partial least-squares regression discriminant analyses (PLS-DA) were performed in order to elucidate the ability of the 1H spectra acquired at various field strengths to identify possible spectral differences and discriminate between pre- and postintervention samples. The loadings from PLS-DA contained the same spectral regions, implying that the same metabolites were involved in the discrimination independent of magnetic field strength. The investigation revealed a strong increase in prediction performance and thereby spectral information content when increasing the magnetic field strength from 250 to 500 MHz, while from 500 to 800 MHz the increase was less pronounced.

Purification and structure characterization of the active component in the pneumococcal 22F polysaccharide capsule used for adsorption in pneumococcal enzyme-linked immunosorbent assays

Protection against pneumococcal disease is thought to be mediated primarily by antibodies that are opsonic [Musher DM, Chapman AJ, Goree A, Jonsson S, Briles D, Baughn RE. Natural and vaccine-related immunity to Streptococcus pneumoniae. J Infect Dis 1986;154(2):245-56]. Pneumococcal capsular polysaccharide (CPS) is immunogenic and induces type-specific protective immunity. For convenience, the protective capacity of serum antibodies is often evaluated by the measurement of antibody titers in an ELISA test. The pneumococcal capsular polysaccharide (CPS) used in ELISA contains several impurities; these include about 5% by weight of teicholic acid (CWPS) and the cholin binding protein, pneumococcal surface protein A (PspA) [Sorensen UB, Henrichsen J. C-polysaccharide in a pneumococcal vaccine. Acta Pathol Microbiol Immunol Scand C 1984;92(6):351-6; Yu J, Briles DE, Englund JA, Hollingshead SK, Glezen WP, Nahm MH. Immunogenic protein contaminants in pneumococcal vaccines. J Infect Dis 2003;187(6):1019-23]. All individuals have antibodies to CWPS possible as a result of early exposure to pneumococci, Streptocuccus mitis and Streptocuccus oralis [Bergstrom N, Jansson PE, Kilian M, Skov Sorensen UB. Structures of two cell wall-associated polysaccharides of a Streptococcus mitis biovar 1 strain. A unique teichoic acid-like polysaccharide and the group O antigen which is a C-polysaccharide in common with pneumococci. Eur J Biochem 2000;267(24):7147-57. [4]]. The concentration of the CWPS antibodies in non-immunized individuals often exceeds the concentration of the serotype-specific pneumococcal antibodies. Therefore, the pneumococcal ELISA requires an adsorption step to remove the unprotective CWPS antibodies [Konradsen HB, Sorensen UB, Henrichsen J. A modified enzyme-linked immunosorbent assay for measuring type-specific anti-pneumococcal capsular polysaccharide antibodies. J Immunol Meth 1993;164(1):13-20. [5]; Concepcion N, Frasch CE. Evaluation of previously assigned antibody concentrations in pneumococcal polysaccharide reference serum 89SF by the method of cross-standardization. Clin Diagn Lab Immunol 1998;5(2):199-204. [6]; Kayhty H, Ahman H, Ronnberg PR, Tillikainen R, Eskola J. Pneumococcal polysaccharide-meningococcal outer membrane protein complex conjugate vaccine is immunogenic in infants and children. J Infect Dis 1995;172(5):1273-8. [7]; Koskela M. Serum antibodies to pneumococcal C polysaccharide in children: response to acute pneumococcal otitis media or to vaccination. Pediatr Infect Dis J 1987;6 (6):519-26. [8]]. Recently a new pneumococcal CPS ELISA was recommended with an extra serum absorption step with 22F CPS to remove antibodies against an extra unknown common cross-reactive component. The aim of this study was to characterize the active component in the 22F capsule. A non-capsulated pneumococci was prepared from a 22F capsulated pneumococci. The cell wall polysaccharide (CWPS2) purified from this pneumococci has a better adsorption potential than 22F capsule in the pneumococci ELISA. Structure characterization of the commercial available CWPS and CWPS2 was done by nuclear magnetic resonance (NMR). The NMR results showed that commercial CWPS had one phosporylcholine per sugar repeat while the CWPS2 had two phosporylcholine per sugar repeat explaining an immunological difference between the two variants of CWPS. In addition the LicD2 gene responsible for the attachment of the second cholin in the CWPS tetra sugar repeat was inactive in the strain used for purifying the commercial CWPS but active in the strain expressing CWPS2.

Studies Directed to Understanding the Structure of Chitosan−Metal Complexes: Investigations of Mono- and Disaccharide Models with Platinum(II) Group Metals

X-ray and NMR experiments were performed with simple chitosan models based on glucosamine monosaccharides and disaccharides to understand the binding properties and structures of the complexes formed between this polysaccharide and platinum(II) metals. Subjection of the glucosamine derivatives with [PdCl2(PhCN)2] provided trans-diamine complexes which upon further treatment with excess (NH4)PF6 generated complexes possessing two 5-membered chelate rings involving the C2-amine and the C3-hydroxyl group of the two individual glucosamine units.

An NMR-based metabonomic investigation on effects of milk and meat protein diets given to 8-year-old boys

The objective of the study was to investigate the ability of an NMR-based metabonomic approach, applied to biofluids, to explore and identify overall exogenous and endogenous biochemical effects of a short-time high intake of milk protein or meat protein given to prepubertal children, the aim being to compare relative differences and not an absolute quantification. A total of twenty-four 8-year-old boys were asked to take 53 g protein as milk (n 12) or meat daily (n 12). At baseline and after 7 d, urine and serum samples were collected and high-resolution 1H NMR spectra were acquired on these using a 800 MHz spectrometer. The milk diet reduced the urinary excretion of hippurate, while the meat diet increased the urinary excretion of creatine, histidine and urea. The NMR measurements on serum revealed minor changes in the lipid profile, which most probably should be ascribed to an increase in the content of SCFA in the blood after consumption of the milk diet. The meat diet had no effect on the metabolic profile of serum. The study for the first time demonstrates the capability of proton NMR-based metabonomics to identify the overall biochemical effects of consumption of different animal proteins. The urine metabolite profile is more susceptible to perturbations as a result of short diet interventions than the serum metabolite profile. The milk diet-induced reduction in urinary excretion of hippurate suggests alterations in gut microflora, which may be useful information for further studies elucidating the effects of bioactive components in milk.

Structural characterisation of novel lichen heteroglycans by NMR spectroscopy and methylation analysis

Two galactofuranomannans, Ths-4 and Ths-5, were isolated from the lichen, Thamnolia vermicularis var. subuliformis, using ethanol fractionation and anion-exchange and size-exclusion chromatography. The average molecular weights of Ths-4 and Ths-5 were estimated to be 19 and 200 kDa, respectively. Structural characterisation of Ths-4, Ths-5 and their partially hydrolysed derivatives was performed by methanolysis and methylation analysis. The intact and partially hydrolysed Ths-4 was further analysed using NMR spectroscopy (1D, COSY, NOESY, TOCSY, HSQC and HMBC). According to the data obtained, the heteroglycans Ths-4 and Ths-5 have similar structures, but have large differences in molecular weight. The structure is composed of 3-O-linked and 5-O-linked galactofuranosyl chains linked to a mannan core. The mannan core consists of a main chain of alpha-(1-->6)-linked mannopyranosyl residues, substituted at O-2 with either a single alpha-mannopyranosyl unit or an alpha-Manp-(1-->2)-alpha-Manp-(1-->2)-alpha-Manp group in the ratio of approximately 1:3, respectively. The polysaccharides have idealised repeating blocks as is shown.

Characterization of the lipopolysaccharide and beta-glucan of the fish pathogen Francisella victoria

Lipopolysaccharide (LPS) and beta-glucan from Francisella victoria, a fish pathogen and close relative of highly virulent mammal pathogen Francisella tularensis, have been analyzed using chemical and spectroscopy methods. The polysaccharide part of the LPS was found to contain a nonrepetitive sequence of 20 monosaccharides as well as alanine, 3-aminobutyric acid, and a novel branched amino acid, thus confirming F. victoria as a unique species. The structure identified composes the largest oligosaccharide elucidated by NMR so far, and was possible to solve using high field NMR with cold probe technology combined with the latest pulse sequences, including the first application of H2BC sequence to oligosaccharides. The non-phosphorylated lipid A region of the LPS was identical to that of other Francisellae, although one of the lipid A components has not been found in Francisella novicida. The heptoseless core-lipid A region of the LPS contained a linear pentasaccharide fragment identical to the corresponding part of F. tularensis and F. novicida LPSs, differing in side-chain substituents. The linkage region of the O-chain also closely resembled that of other Francisella. LPS preparation contained two characteristic glucans, previously observed as components of LPS preparations from other strains of Francisella: amylose and the unusual beta-(1-6)-glucan with (glycerol)2phosphate at the reducing end.

Complete structures of Bordetella bronchiseptica and Bordetella parapertussis lipopolysaccharides

The structures of the lipopolysaccharide (LPS) core and O antigen of Bordetella bronchiseptica and Bordetella parapertussis are known, but how these two regions are linked to each other had not been determined. We have studied LPS from several strains of these microorganisms to determine the complete carbohydrate structure of the LPS. LPS was analyzed using different chemical degradations, NMR spectroscopy, and mass spectrometry. This identified a novel pentasaccharide fragment that links the O chain to the core in all the LPS studied. In addition, although the O chain of these bacteria was reported as a homopolymer of 1,4-linked 2,3-diacetamido-2,3-dideoxy-alpha-galacturonic acid, we discovered that the polymer contains several amidated uronic acids, the number of which varies between strains. These new data describe the complete structure of the LPS carbohydrate backbone for both Bordetella species and help to explain the complex genetics of LPS biosynthesis in these bacteria.

H2BC: a new technique for NMR analysis of complex carbohydrates

It is demonstrated that the H2BC NMR pulse sequence (J. Am. Chem. Soc.2005, 127, 6154, Magn. Reson. Chem.2005, 43, 971-974) offers unambiguous assignments and significant simplification of NMR spectra of large and complex carbohydrates compared to other techniques for the establishment of correlations over more than one bond. H2BC almost exclusively correlates protons and proton-bearing carbon spins separated by two covalent bonds and is independent of occasionally vanishing (2)J(CH) coupling constants, which alleviates the problem of missing two-bond correlations in HMBC spectra. H2BC also solves the problem of distinguishing two- and three-bond correlations in HSQC-TOCSY or HMBC. It is a further asset of H2BC that the experiment is significantly shorter than HMBC and HSQC-TOCSY, and hence less sensitive to transverse relaxation. The H2BC experiment is demonstrated on an approximately 30-residue oligosaccharide from Francisella victoria.

Substrate specificity of the bovine serum amine oxidase and in situ characterisation of aminoaldehydes by NMR spectroscopy

The oxidation of spermidine or homospermidine with bovine serum amine oxidase (BSAO) was monitored in situ, using proton nuclear magnetic resonance spectroscopy in water with 10% D(2)O. NMR assignments were performed by spin decoupling and COSY spectra or by comparison with data from synthetic aminoaldehydes. The results represent the first in situ characterisation of the highly reactive aminoaldehydes and showed oxidation at the N(1) amino group of spermidine and homospermidine. Comparison of homospermidine with a variety of substrates revealed that among straight chain di- and polyamines both an aminopropyl group and two primary amino groups separated by seven (norspermidine) or eight (spermidine) carbon atoms were required for optimal substrate ability. However, highest activity was seen with the substrate N-(4-aminobutyl)hexahydropyrimidine, showing that the substrate channel of BSAO has a dual substrate preference, with moderately bulky substituents at the distal end of a diamine contributing equally well as an alkyl amino group. Cytotoxic investigations of a variety of substrates for BSAO, confirmed previous results, that cytotoxicity is primarily linked to polyamines encompassing the aminopropyl moiety. No acrolein was observed at any time during the oxidation showing that it reacts very fast with available amino groups forming a variety of derivatives.

Discovery of new natural products by application of X-hitting, a novel algorithm for automated comparison of full UV spectra, combined with structural determination by NMR spectroscopy

X-hitting, a newly developed algorithm for automated comparison of UV data, has been used for the tracking of two novel spiro-quinazoline metabolites, lapatins A (1) and B (2), in a screening study targeting quinazolines. The structures of 1 and 2 were elucidated by analysis of spectroscopic data, primarily 2D NMR.

Two Novel Types of O-Glycans on the Mugwort Pollen Allergen Art v 1 and Their Role in Antibody Binding

Art v 1, the major allergen of mugwort (Artemisia vulgaris) pollen contains galactose and arabinose. As the sera of some allergic patients react with natural but not with recombinant Art v 1 produced in bacteria, the glycosylation of Art v 1 may play a role in IgE binding and human allergic reactions. Chemical and enzymatic degradation, mass spectrometry, and 800 MHz (1)H and (13)C nuclear magnetic resonance spectroscopy indicated the proline-rich domain to be glycosylated in two ways. We found a large hydroxyproline-linked arabinogalactan composed of a short beta1,6-galactan core, which is substituted by a variable number (5-28) of alpha-arabinofuranose residues, which form branched side chains with 5-, 2,5-, 3,5-, and 2,3,5-substituted arabinoses. Thus, the design of the Art v 1 polysaccharide differs from that of the well known type II arabinogalactans, and we suggest it be named type III arabinogalactan. The other type of glycosylation was formed by single (but adjacent) beta-arabinofuranoses linked to hydroxyproline. In contrast to the arabinosylation of Ser-Hyp(4) motifs in other hydroxyproline-rich glycoproteins, such as extensins or solanaceous lectins, no oligo-arabinosides were found in Art v 1. Art v 1 and parts thereof produced by alkaline degradation, chemical deglycosylation, proteolytic degradation, and/or digestion with alpha-arabinofuranosidase were used in enzyme-linked immunosorbent assay and immunoblot experiments with rabbit serum and with the sera of patients. Although we could not observe antibody binding by the polysaccharide, the single hydroxyproline-linked beta-arabinose residues appeared to react with the antibodies. Mono-beta-arabinosylated hydroxyproline residues thus constitute a new, potentially cross-reactive, carbohydrate determinant in plant proteins.

Hesseltin A, a Novel Antiviral Metabolite from Penicillium hesseltinei

[structure: see text] Hesseltin A 1, a novel compound of mixed polyketide-terpenoid origins was isolated from the filamentous fungus Penicillium hesseltinei. The structure and stereochemistry were determined from extensive one- and two-dimensional NMR and mass spectral data.

The structure of the glucuronoxylomannan produced by culinary-medicinal yellow brain mushroom (Tremella mesenterica Ritz.:Fr., Heterobasidiomycetes) grown as one cell biomass in submerged culture

The yellow brain mushroom Tremella mesenterica possesses a wide spectrum of medicinal properties, including immunostimulating, protecting against radiation, antidiabetic, anti-inflammatory, hypocholesterolemic, hepatoprotective, and antiallergic effects. A unique feature of T. mesenterica is that most of the above mentioned medicinal properties depend on glucuronoxylomannan (GXM) contained in fruiting bodies or produced in pure culture conditions. We developed a new strain of T. mesenterica CBS 101939, which grows in submerged culture and offers superior yields of one-cell biomass rich in exocellular heteropolysaccharide GXM. The structure of the GXM was analyzed by NMR spectroscopy and chemical methods. The polysaccharide has a defined repeating unit structure, which is O-acetylated at several points: [structure: see text]. These results differ from previously published structure of Tremella extracellular polysaccharides, where mannan backbone was believed to be randomly glycosylated with xylan chains of different length.