scholarly journals Interactions of sialic acid with phosphatidylcholine liposomes studied by 2D NMR spectroscopy.

2013 ◽  
Vol 60 (4) ◽  
Author(s):  
Anna Timoszyk ◽  
Lidia Latanowicz
Keyword(s):  
Sialic Acid ◽  
Dipole Interaction ◽  
2D Nmr ◽  
Membrane Dynamics ◽  
Phospholipid Bilayer ◽  
Acid Molecule ◽  
2D Nmr Spectroscopy ◽  
Acetylneuraminic Acid ◽  
Long Time ◽  
Chemical Groups

Biological membranes are complex systems which have attracted scientific interest for a long time and for various reasons. The sialic acid-liposome interactions at the molecular level depend on their hydro-lipophilic characteristics. The aim of the present study was to investigate the changes of conformation of the phospholipid (1,2-Diacyl-sn-glycero-3-phosphocholine) and sialic acid (2,8-(N-acetylneuraminic acid)) molecules and the type of interactions induced by the sialic acid molecules on membrane-like systems (liposomes) by 2D NMR (TOCSY, HETCOR, ROESY). The nature of the interaction of sialic acid with the model membrane depends on the structure of the phospholipid headgroups and the hydration of membrane. In ROESY spectra was observed the absence of dipole-dipole couplings within the choline head, between headgroups and glycerol, and between glycerol and fatty acid chains. It indicates an increase of the membrane dynamics in the presence of sialic acid. Moreover, the conformation of sialic acid molecule is changed in the presence of liposomes, which depends on stereochemistry of the chemical groups of the carbon atoms C7 and C8, and oxygen O8. The observed differences between the ROESY spectra of free and liposome bound sialic acid may be a consequence of a changed orientation of the pyranose ring from trans to gauche in the presence of liposomes. The sialic acid penetrate into the phospholipid bilayer to a sufficient depth to allow the dipole interaction. The present result that the correlation signal was found only between the methyl protons from the acetyl group of sialic acid and the methylene tail of phospholipid molecule in the ROESY spectrum indicates that the opposite end of the sialic acid molecule stays in the aqueous phase without interacting with membrane molecules.

scholarly journals Uncovering a novel molecular mechanism for scavenging sialic acids in bacteria

2020 ◽  
Vol 295 (40) ◽  
pp. 13724-13736 ◽  
Author(s):  
Andrew Bell ◽  
Emmanuele Severi ◽  
Micah Lee ◽  
Serena Monaco ◽  
Dimitrios Latousakis ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Molecular Mechanism ◽  
Molecular Mechanisms ◽  
Bacterial Species ◽  
2D Nmr ◽  
Site Directed Mutagenesis ◽  
Bioinformatics Analyses ◽  
E Coli ◽  
Acetylneuraminic Acid ◽  
Protein Dimer

The human gut symbiont Ruminococcus gnavus scavenges host-derived N-acetylneuraminic acid (Neu5Ac) from mucins by converting it to 2,7-anhydro-Neu5Ac. We previously showed that 2,7-anhydro-Neu5Ac is transported into R. gnavus ATCC 29149 before being converted back to Neu5Ac for further metabolic processing. However, the molecular mechanism leading to the conversion of 2,7-anhydro-Neu5Ac to Neu5Ac remained elusive. Using 1D and 2D NMR, we elucidated the multistep enzymatic mechanism of the oxidoreductase (RgNanOx) that leads to the reversible conversion of 2,7-anhydro-Neu5Ac to Neu5Ac through formation of a 4-keto-2-deoxy-2,3-dehydro-N-acetylneuraminic acid intermediate and NAD+ regeneration. The crystal structure of RgNanOx in complex with the NAD+ cofactor showed a protein dimer with a Rossman fold. Guided by the RgNanOx structure, we identified catalytic residues by site-directed mutagenesis. Bioinformatics analyses revealed the presence of RgNanOx homologues across Gram-negative and Gram-positive bacterial species and co-occurrence with sialic acid transporters. We showed by electrospray ionization spray MS that the Escherichia coli homologue YjhC displayed activity against 2,7-anhydro-Neu5Ac and that E. coli could catabolize 2,7-anhydro-Neu5Ac. Differential scanning fluorimetry analyses confirmed the binding of YjhC to the substrates 2,7-anhydro-Neu5Ac and Neu5Ac, as well as to co-factors NAD and NADH. Finally, using E. coli mutants and complementation growth assays, we demonstrated that 2,7-anhydro-Neu5Ac catabolism in E. coli depended on YjhC and on the predicted sialic acid transporter YjhB. These results revealed the molecular mechanisms of 2,7-anhydro-Neu5Ac catabolism across bacterial species and a novel sialic acid transport and catabolism pathway in E. coli.

Demonstration of 2D NMR Spectroscopy in a Powered Magnet at 25 T Using Cascade Field Regulation

2019 ◽  
Author(s):  
Benjamin D. McPheron ◽  
Jeffrey L. Schiano ◽  
Brian F. Thomson ◽  
Kiran K. Shetty ◽  
William W. Brey
Keyword(s):  
Nmr Spectroscopy ◽  
2D Nmr ◽  
2D Nmr Spectroscopy

scholarly journals The fate of orally administered sialic acid: First insights from patients with N-acetylneuraminic acid synthase deficiency and control subjects

2021 ◽  
Vol 28 ◽  
pp. 100777
Author(s):  
Christel Tran ◽  
Licia Turolla ◽  
Diana Ballhausen ◽  
Sandrine Cornaz Buros ◽  
Tony Teav ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Acetylneuraminic Acid ◽  
Control Subjects ◽  
And Control

scholarly journals 5-((8-Hydroxyquinolin-5-yl)diazenyl)-3-methyl-1H-pyrazole-4-carboxylic Acid

Molbank ◽  
10.3390/m1238 ◽  
2021 ◽  
Vol 2021 (2) ◽  
pp. M1238
Author(s):  
Ion Burcă ◽  
Valentin Badea ◽  
Calin Deleanu ◽  
Vasile-Nicolae Bercean
Keyword(s):  
Chemical Structure ◽  
Functional Group ◽  
Coupling Reaction ◽  
2D Nmr ◽  
Azo Coupling ◽  
2D Nmr Spectroscopy ◽  
Azo Compound ◽  
Ft Ir ◽  
New Compounds ◽  
Carboxylic Functional Group

A new azo compound was prepared via the azo coupling reaction between 4-(ethoxycarbonyl)-3-methyl-1H-pyrazole-5-diazonium chloride and 8-hydroxyquinoline (oxine). The ester functional group of the obtained compound was hydrolyzed and thus a new chemical structure with a carboxylic functional group resulted. The structures of the new compounds were fully characterized by: UV–Vis, FT-IR, 1D and 2D NMR spectroscopy, and HRMS spectrometry.

scholarly journals Ambient-Temperature Synthesis of (E)-N-(3-(tert-Butyl)-1-methyl-1H-pyrazol-5-yl)-1-(pyridin-2-yl)methanimine

Molbank ◽  
10.3390/m1250 ◽  
2021 ◽  
Vol 2021 (3) ◽  
pp. M1250
Author(s):  
Diana Becerra ◽  
Justo Cobo ◽  
Juan-Carlos Castillo
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Ambient Temperature ◽  
Magnesium Sulfate ◽  
Elemental Analysis ◽  
Condensation Reaction ◽  
2D Nmr ◽  
2D Nmr Spectroscopy ◽  
Temperature Synthesis ◽  
Tert Butyl

We report the ambient-temperature synthesis of novel (E)-N-(3-(tert-butyl)-1-methyl-1H-pyrazol-5-yl)-1-(pyridin-2-yl)methanamine 3 in 81% yield by a condensation reaction between 3-(tert-butyl)-1-methyl-1H-pyrazol-5-amine 1 and 2-pyridinecarboxaldehyde 2 in methanol using magnesium sulfate as a drying agent. The N-pyrazolyl imine 3 was full characterized by IR, 1D, and 2D NMR spectroscopy, mass spectrometry, and elemental analysis.

Highly NIR-emitting ytterbium complexes containing 2-(tosylaminobenzylidene)-N-benzoylhydrazone anions: structure in solution and use for bioimaging

2021 ◽  
Author(s):  
Anton D Kovalenko ◽  
Alexander A. Pavlov ◽  
Ilya D. Ustinovich ◽  
Alena S. Kalyakina ◽  
Alexander S Goloveshkin ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Lanthanide Complexes ◽  
2D Nmr ◽  
2D Nmr Spectroscopy ◽  
Ytterbium Complexes ◽  
Solution Behaviour ◽  
Structure In Solution

Abstract: Solution behaviour in DMSO using 1D and 2D NMR spectroscopy was performed for lanthanide complexes Ln(L)(HL) and Ln(HL)2Cl, containing non-macrocyclic 2-(tosylamino)-benzylidene-N-benzoylhydrazone (H2L), and the structure of [Yb(L)]+ cation in...

scholarly journals ent-Kaurane Diterpenes from Annona glabra and Their Cytotoxic Activities

2014 ◽  
Vol 9 (12) ◽  
pp. 1934578X1400901
Author(s):  
Hoang Le Tuan Anh ◽  
Nguyen Thi Thu Hien ◽  
Dan Thi Thuy Hang ◽  
Tran Minh Ha ◽  
Nguyen Xuan Nhiem ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cancer Cell ◽  
Human Cancer ◽  
2D Nmr ◽  
Cancer Cell Lines ◽  
Cytotoxic Activities ◽  
Human Cancer Cell ◽  
2D Nmr Spectroscopy ◽  
Human Cancer Cell Lines ◽  
Annona Glabra

A new ent-kaurane glycoside, annoglabasin H (1), and three known ent-kauranes, annoglabasin E (2), annoglabasin B (3), and 19-nor- ent-kaurent-4-ol-17-oic acid (4) were isolated from the fruits of Annona glabra. Their structures were determined by the combination of spectroscopic and chemical methods, including 1D- and 2D-NMR spectroscopy, as well as by comparison with the NMR data reported in the literature. The cytotoxic activities of these compounds were evaluated on four human cancer cell lines, LU-1, MCF-7, SK-Mel2, and KB. Compound 1 exhibited significant cytotoxic activity on all tested human cancer cell lines with IC50 values ranging from 3.7 to 4.6 μM.

scholarly journals NMR-Based Structural Characterization of a Two-Disulfide-Bonded Analogue of the FXIIIa Inhibitor Tridegin: New Insights into Structure–Activity Relationships

2021 ◽  
Vol 22 (2) ◽  
pp. 880
Author(s):  
Thomas Schmitz ◽  
Ajay Abisheck Paul George ◽  
Britta Nubbemeyer ◽  
Charlotte A. Bäuml ◽  
Torsten Steinmetzer ◽  
...  
Keyword(s):  
Structural Information ◽  
Coagulation Factor ◽  
Md Simulations ◽  
2D Nmr ◽  
Label Free ◽  
2D Nmr Spectroscopy ◽  
Structure Information ◽  
Structure Activity Relationships ◽  
Structure Activity ◽  
Blood Sucking

The saliva of blood-sucking leeches contains a plethora of anticoagulant substances. One of these compounds derived from Haementeria ghilianii, the 66mer three-disulfide-bonded peptide tridegin, specifically inhibits the blood coagulation factor FXIIIa. Tridegin represents a potential tool for antithrombotic and thrombolytic therapy. We recently synthesized two-disulfide-bonded tridegin variants, which retained their inhibitory potential. For further lead optimization, however, structure information is required. We thus analyzed the structure of a two-disulfide-bonded tridegin isomer by solution 2D NMR spectroscopy in a combinatory approach with subsequent MD simulations. The isomer was studied using two fragments, i.e., the disulfide-bonded N-terminal (Lys1–Cys37) and the flexible C-terminal part (Arg38–Glu66), which allowed for a simplified, label-free NMR-structure elucidation of the 66mer peptide. The structural information was subsequently used in molecular modeling and docking studies to provide insights into the structure–activity relationships. The present study will prospectively support the development of anticoagulant-therapy-relevant compounds targeting FXIIIa.

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