Discovery of a New, Recurrent Enzyme in Bacterial Phosphonate Degradation: ()-1-Hydroxy-2-aminoethylphosphonate Ammonia-lyase.

Phosphonates represent an important source of bioavailable phosphorus in certain environments. Accordingly, many microorganisms (particularly marine bacteria) possess catabolic pathways to degrade these molecules. One example is the widespread hydrolytic route for the breakdown of 2-aminoethylphosphonate (AEP, the most common biogenic phosphonate).

Toxic metal sequential sequestration in water using new amido-aminoacid ligand as a model for the interaction with polyamidoamines.

Polyamidoamines are low cost and easily synthesized materials that may find applications in cations sequestration and water treatment. In this paper a new amido-aminoacid ligand containing methionine has been designed as a monomeric model of the corresponding polyamidoamine. The amido-aminoacid ligand has been synthesized in high yield, by reacting acrylamide and methionine via aza-Michael addition in water and mild temperature conditions.

Birth of a pathway for sulfur metabolism in early amniote evolution.

Among amniotes, reptiles and mammals are differently adapted to terrestrial life. It is generally appreciated that terrestrialization required adaptive changes of vertebrate metabolism, particularly in the mode of nitrogen excretion. However, the current paradigm is that metabolic adaptation to life on land did not involve synthesis of enzymatic pathways de novo, but rather repurposing of existing ones.

A community-built calibration system: The case study of quantification of metabolites in grape juice by qNMR spectroscopy.

Nuclear Magnetic Resonance (NMR) is an analytical technique extensively used in almost every chemical laboratory for structural identification. This technique provides statistically equivalent signals in spite of using spectrometer with different hardware features and is successfully used for the traceability and quantification of analytes in food samples. Nevertheless, to date only a few internationally agreed guidelines have been reported on the use of NMR for quantitative analysis.

Nuclear Magnetic Resonance of Gangliosides.

Structure, conformation, and dynamics of sphingolipids can provide substantial help in better understanding sphingolipid-ligand interaction mechanisms. Both the oligosaccharide structure and the ceramide moiety of native glycosphingolipid can be established directly by NMR spectroscopic analysis without the necessity to resort to any other chemical or spectroscopic methods. NMR is a powerful technique to investigate interaction between small ligand, such as ganglioside, and membrane protein.

HR MAS H NMR and chemometrics as useful tool to assess the geographical origin of cocoa beans - Comparison with HR H NMR.

Chocolate and cocoa-based products are among the goods with higher added value. A current trend of the cocoa market is to offer to the consumers high quality cocoa products, namely mono-origin cocoa. However, a reliable analytical method able to trace the geographical origin of cocoa is lacking.

Performance Assessment in Fingerprinting and Multi Component Quantitative NMR Analyses.

An interlaboratory comparison (ILC) was organized with the aim to set up quality control indicators suitable for multicomponent quantitative analysis by nuclear magnetic resonance (NMR) spectroscopy. A total of 36 NMR data sets (corresponding to 1260 NMR spectra) were produced by 30 participants using 34 NMR spectrometers. The calibration line method was chosen for the quantification of a five-component model mixture.

Application of 1H NMR for the characterisation of cocoa beans of different geographical origins and fermentation levels.

This study reports for the first time the use of (1)H NMR technique combined with chemometrics to study the metabolic profile of cocoa (Theobroma cacao L.) beans of different varieties, origin and fermentation levels. Results of PCA applied to cocoa bean (1)H NMR dataset showed that the main factor influencing the cocoa bean metabolic profile is the fermentation level.

Application of ¹H NMR for the characterisation and authentication of ''Tonda Gentile Trilobata" hazelnuts from Piedmont (Italy).

The Italian hazelnut (Corylus avellana L.) cultivar "Tonda Gentile Trilobata" (TGT) is covered by protected geographical indication "Nocciola Piemonte" and is well-known as the best-suited hazelnut for the industrial transformation into roasted kernel. The hazelnut cultivar identification is primarily based on morphological characteristics, so there is the need for more objective analytical methods for high quality hazelnut authentication.

1H NMR study of fermented cocoa (Theobroma cacao L.) beans.

This study reports for the first time the metabolic profile of cocoa (Theobroma cacao L.) beans using the (1)H NMR technique applied to polar extracts of fermented cocoa beans. The simultaneous detection and quantification of amino acids, polyalcohols, organic acids, sugars, methylxanthines, catechins, and phenols were obtained by assigning the major signals of the spectra for different varieties of cocoa beans (Forastero, Criollo, and Trinitario) from different countries (Ecuador, Ghana, Grenada, and Trinidad).

NMR analysis of a series of imidazobenzoxazines.

The complete (1)H and (13)C NMR assignment of a series of imidazobenzoxazines by a combination of one- and two-dimensional experiments (COSY, HSQC and HMBC) is studied. Moreover, 2D NOESY and 1D selective NOESY are reported. This procedure allows the identification of the regioisomers obtained.

Complete 1H and 13C NMR spectral assignment of benzo[d]isothiazole derivatives and of an isoindole isoster.

The complete (1)H and (13)C NMR assignments of the novel compound methyl 2-amino-3-(benzo[d]isothiazol-3-yl)propanoate (1), of 3-amino-5-methylbenzo[d]isothiazole (2) and N-(t-butyloxycarbonyl)-2-aminobenzo[d]isothiazol-3(2H)-one (3) and of the desulfurated isostere of 3, N-(t-butyloxycarbonyl)-2-aminoisoindolin-1-one (4), using 1D and 2D NMR techniques, including COSY, INADEQUATE, HSQC, and HMBC experiments are reported.

Identification and quantification of the main organic components of vinegars by high resolution 1H NMR spectroscopy.

A detailed analysis of the proton high-field NMR spectra of vinegars (in particular of Italian balsamic vinegars) is reported. A large number of organic substances belonging to different classes, such as carbohydrates, alcohols, organic acids, volatile compounds and amino acids, were assigned. The possibility of quantification of the substances identified in the whole vinegar sample, without extraction or pre-concentration steps, was also tested.

Reactivity of Ph2P(Se)CH2C6H4CH2P(Se)Ph2 with [M3(CO)12] (M=Ru or Fe). Synthesis and characterization of the new carbene cluster [Ru3(mu3-Se)(mu3-H)(mu2-PPh2)(CO)6(mu2-CHC6H4CH2PPh2)].

The reactions of [M3(CO)12] (M=Ru or Fe) with 1,2 bis[(diphenylphosphino)methyl]benzene diselenide (dpmbSe2) in hot toluene afford a variety of phosphine-substituted selenido carbonyl clusters. They belong to the following three families: (i) 50-electron clusters with a M3Se2 core (2, 3, 5-7), (ii) 48-electron clusters with a M3Se core (1, 8), (iii) 34-electron clusters with a M2Se2 core (4). All these species derive from the P=Se bond cleavage.

Variable strategy toward carbasugars and relatives. 4. Viable access to (4a-carbapentofuranosyl)amines, (5a-carbahexopyranosyl)amines, and amino acids thereof.

A chiral, divergent synthesis of two carbafuranosylamines, 1 and 2, two carbapyranosylamines, 3 and 4, two carbafuranosylamino acids, 5 and 6, and two carbapyranosylamino acids, 7 and 8, has been achieved. Highlights of the procedure include the following: a diastereoselective crossed vinylogous Mukaiyama aldol coupling between N-(tert-butoxycarbonyl)-2-[(tert-butyldimethylsilyl)oxy]pyrrole (TBSOP, 9) and 2,3-O-isopropylidene-D-glyceraldehyde (10) for the assembly of the target compound carbon backbone; a high-yielding silylative cycloaldolization that gives the cyclopentanoid and cyclohexanoid motifs; and a reductive or hydrolytic breakage of the lactam C(O)-N link to liberate the carbasugar and install the desired pseudo-anomeric amine and the hydroxymethyl or carboxyl functionalities. The sequences leading to trans-configured carbafuranosyl compounds 1 and 5 and carbapyranosyl compounds 3 and 7 were 12- and 13-step processes, with overall yields of 34%, 35%, 17%, and 16%.

Variable strategy toward carbasugars and relatives. 2. Diversity-based synthesis of beta-D-xylo, beta-D-ribo, beta-L-arabino, and beta-L-lyxo 4a-carbafuranoses and (4a-carbafuranosyl)thiols.

The silyloxy diene-based construction of carbasugars, previously exploited for the synthesis of four carbocyclic furanose and pyranose analogues, has been investigated further. By introducing a novel silylative cycloaldolization protocol and by adjusting a couple of minor transformations, the efficiency of this synthetic sequence was greatly improved. Through a series of lactone/thiolactone aldehyde cyclization precursors, four carbafuranoses (4a-carba-beta-D-xylofuranose, 4a-carba-beta-D-ribofuranose, 4a-carba-beta-L-arabinofuranose, and 4a-carba-beta-L-lyxofuranose) and four (carbafuranosyl)thiols [(4a-carba-beta-D-xylofuranosyl)thiol, (4a-carba-beta-D-ribofuranosyl)thiol, (4a-carba-beta-L-arabinofuranosyl)thiol, and (4a-carba-beta-L-lyxofuranosyl)thiol] were assembled.

Variable strategy toward carbasugars and relatives. 1. Stereocontrolled synthesis of pseudo-beta-D-gulopyranose, pseudo-beta-D-xylofuranose, (pseudo-beta-D-gulopyranosyl)amine, and (pseudo-beta-D-xylofuranosyl)amine.

Four novel, chiral nonracemic carbasugars have been synthesized from 1,2-O-isopropylidene-D-glyceraldehyde. Furan- and pyrrole-based 2-silyloxy dienes--mimics of the alpha,gamma-dianions of gamma-hydroxy- and gamma-aminobutanoic acid, respectively--nicely served to complete the syntheses of two all-oxygen compounds, pseudo-beta-D-gulopyranose and pseudo-beta-D-xylofuranose, and two "anomeric" amino derivatives, (pseudo-beta-D-gulopyranosyl)amine (1,2,4-tri-epi-validamine) and (pseudo-beta-D-xylofuranosyl)amine. Two sequential, highly diastereoselective carbon-carbon bond-forming maneuvers, i.

The utility of furan-, pyrrole-, and thiophene-based 2-silyloxy dienes as demonstrated by modular synthesis of annonaceous acetogenin core units and their pyrrolidine and thiolane analogues.

We report a modular strategy for obtaining the core units of annonaceous acetogenins and their nitrogen and sulfur analogues, which generates great structural diversity. This synthesis is based on the application of a reiterative vinylogous addition protocol involving a unique triad of silyloxy diene modules, 2-[(tert-butyldimethylsilyl)oxy]furan (TBSOF), N-(tert-butoxycarbonyl)-2-[(tert-butyldimethylsilyl)oxy]pyrrole (TBSOP), and 2-[(tert-butyldimethylsilyl)oxy]thiophene (TBSOT) and suitable heteroatom-stabilized carbenium ions. By combining TBSOF, TBSOP, and TBSOT nucleophilic synthons with certain tetrahydrofuran, pyrrolidine, and thiolane acceptors, the construction of varied, adjacently linked oligo-heterocyclic motifs related to the core segments of the annonaceous acetogenins is assured.

The structural basis for the susceptibility of gangliosides to enzymatic degradation.

The conformational properties of GM2, GalNacbeta-4(Neu5Acalpha-3) Galbeta-4Glcbeta-1Cer have been compared to those of 6'-GM2, in which the linkage between the GalNAc and Gal was altered from GalNacbeta-4Galbeta- to GalNacbeta-6Galbeta-, and to those of GD1a, Neu5Acalpha-3Galbeta-3GalNAcbeta-4(Neu5Acalpha-3 )Galbeta-4Glcbeta-1Cer, and GalNAc-GD1a. Our results revealed that unlike the compact and rigid oligosaccharide head group found in GM2, where the Neu5Ac and the GalNAc residues interact, the sugar chain of 6'-GM2 is in an open spatial arrangement, with the Neu5Ac no longer interacting with GalNAc, freely accessible to external interactions. The structure of GD1a can be regarded as that of GM2 with an extension of the terminal Neu5Acalpha-3Galbeta-disaccharide.

Nuclear Overhauser effect investigation on GM1 ganglioside containing N-glycolyl-neuraminic acid (II3Neu5GcGgOse4Cer).

The conformational properties of the oligosaccharide chain of GM1 ganglioside containing N-glycolyl-neuraminic acid, beta-Gal-(1-3)-beta-GalNAc-(1-4)-[alpha-Neu5Gc-(2-3)]-beta-Gal- (1-4)1-4)-beta-Glc-(1-1)-Cer, were studied through NMR nuclear Overhauser effect investigations on the monomeric ganglioside in dimethylsulfoxide, and on mixed micelles of ganglioside and dodecylphosphocholine in water. Several interresidual contacts for the trisaccharide core -beta- GalNAc-(1-4)-[alpha-Neu5Gc-(2-3)]-beta-Gal- were found to fix the relative orientation of the three saccharides, while the glycosidic linkage of the terminal beta-Gal- was found to be quite mobile as the beta-Gal-(1-3)-beta-GalNAc- disaccharide exists in different conformations. These results are similar to those found for two GM1 gangliosides containing N-acetyl-neuraminic acid and neuraminic acid [1].

Geometrical and conformational properties of ganglioside GalNAc-GD1a, IV4GalNAcIV3Neu5AcII3Neu5AcGgOse4Cer.

The aggregative properties of GalNAc-GD1a ganglioside, in comparison with those of GD1a, have been investigated and correlated to the intrinsic conformation and mobility of the oligosaccharide chain of the molecules. Micellar parameters in aqueous solution (molecular mass, hydrodynamic radius as well as the surface area at the lipid/water interface and the packing parameter of the monomer inserted in the aggregate) are measured by the laser light-scattering technique. The presence of a further GalNAc residue causes a 22% increase in molecular mass, contrary to expectation.

Fluorescence excimer formation imaging: a new technique to investigate association to cells and membrane behavior of glycolipids.

A new fluorescence ratio imaging technique aiming to monitor the lateral distribution of pyrene-labeled lipids in the membranes through visualization of the excimer/monomer (E/M) intensity ratio, has been set up, studying the association of a fluorescent derivative of GM1 ganglioside (pyreneGM1) to rat cerebellar granule cells in culture. The imaging results show that the mean E/M ratio value, under experimental conditions leading to the association of pyreneGM1 with the plasma membrane, is significantly higher in neuritic processes than in cell bodies and, moreover, locally distributed in patches. Fluorescence antisotropy imaging of the fluorescent probe TMA-DPH (trimethylaminodiphenylhexatriene) shows the presence of domains having different fluidity and that the average fluidity is higher in cell bodies than in neuritic processes.

Some structural features of cluster-coordinating cysteines of Clostridium pasteurianum ferredoxin are revealed by 2D TOCSY 1H NMR on the oxidized protein.

Different sets of geminal J coupling constants for the eight beta-CH2 protons in the iron-coordinating cysteines in Clostridium pasteurianum ferredoxin were detected by 2D TOCSY 1H NMR experiments on the oxidized protein. Four resonances were characterized by quite similar high values of J, two more resonances had a J value about half of the former ones, while the last two had extremely low J values. These findings suggest that the cysteines required for cubane symmetry around the iron atoms are constrained into different geometries.

Aggregative properties of gangliosides in solution.

The aggregative properties of gangliosides in diluted aqueous solutions are discussed on the basis of simple and well-established thermodynamic concepts. Theoretical assumptions are compared with experimental data obtained, mainly by scattering techniques, on GM3, GM2, GM1, GD1a, GalNAc-GD1a, GD1b, GD1b lactone and GT1b gangliosides, all containing ceramide portions of similar composition, and on GM1 molecular species containing different well-defined ceramide structures. We also report on mixed aggregates with amphiphilic compounds and on the ganglioside aggregate-soluble protein interaction effects which give rise to very stable lipoproteic complexes of well-defined ganglioside-protein composition.