1H NMR studies on the solution conformation of the [L-Ser10] and [D-Ser10] analogues of contulakin-G

2005 ◽  
Vol 83 (2) ◽  
pp. 156-165 ◽  
Author(s):  
Lill Kindahl ◽  
Lennart Kenne ◽  
Corine Sandström
Keyword(s):  
Hydrogen Bond ◽  
Biological Data ◽  
Random Coil ◽  
Solution Conformation ◽  
Nmr Studies ◽  
Peptide Backbone ◽  
H Nmr ◽  
Nmr Data ◽  
Nmr Study ◽  
C Terminus

The synthesis of the O-glycosylated serine-10 analogue of contulakin-G yielded both the [L-] and the [D-Ser10] analogues. The 1H NMR study indicated that the sugars of the two Ser10-glycosylated peptides lacked the hydrogen bond to the peptide backbone that exists in contulakin-G. NOEs showed that the glycan part of the [D-Ser10] analogue had a different orientation to the peptide backbone than that of the [L-Ser10] analogue. The peptide backbones in the two compounds were found to exist mainly in random coil conformations, with transient turns at the site of glycosylation. A transient turn was also found at the C-terminus of the [D-Ser10] glycopeptide. The NMR data indicated that the average conformation of the [D-Ser10] analogue resembles the conformation of contulakin-G more than the [L-Ser] does. Since biological data showed that the [D-Ser10] glycopeptide was as active as contulakin-G, while the [L-Ser10] glycopeptide was only slightly active at more than 100 times the dose, it is possible that it is the orientation of the glycan relative to the peptide chain that is actually recognized by the proteolytic enzyme.Key words: conformation, contulakin-G analogues, NMR, O-linked glycopeptide.

1H NMR studies on the solution conformation of contulakin-G and analogues

2002 ◽  
Vol 80 (8) ◽  
pp. 1022-1031 ◽  
Author(s):  
Lill Kindahl ◽  
Corine Sandström ◽  
A Grey Craig ◽  
Thomas Norberg ◽  
Lennart Kenne
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shifts ◽  
Torsional Rigidity ◽  
Peptide Chain ◽  
Random Coil ◽  
Amide Proton ◽  
Solution Conformation ◽  
Nmr Studies ◽  
H Nmr ◽  
Intramolecular Hydrogen

The conformation of contulakin-G, a bioactive 16 amino acid O-linked glycopeptide (ZSEEGGSNAT*KKPYIL) with the disaccharide β-D-Gal(1[Formula: see text]3)α-D-GalNAc attached to the threonine residue in position 10, has been investigated by 1H NMR spectroscopy. The 1H NMR data for the non-glycosylated peptide and for two glycopeptide analogues, one with the monosaccharide α-D-GalNAc at Thr10 and one with the disaccharide β-D-Gal(1–>3)α-D-GalNAc at Ser7, all of lower bioactivity than contulakin-G, have also been collected. The chemical shifts, NOEs, temperature coefficients of amide protons, and 3JNH,αH-values suggest that all four compounds exist mainly in random coil conformations. Some transient populations of folded conformations are also present in the glycopeptides and turns, probably induced by the sugars, are present in the peptide chain around the site of glycosylation. In the two peptides O-glycosylated at Thr10, the rotation of α-D-GalNAc around the linkage between the sugar and the peptide is restricted. There is evidence for a hydrogen bond between the amide proton of α-D-GalNAc and the peptide chain that could contribute to this torsional rigidity. An intramolecular hydrogen bond between the carbohydrate and the peptide chain does not exist in the peptide O-glycosylated at the Ser7 residue. Key words: conformation, contulakin-G, NMR, O-linked glycopeptide.

Estimating the energy of intramolecular hydrogen bonds from1H NMR and QTAIM calculations

2016 ◽  
Vol 14 (47) ◽  
pp. 11199-11211 ◽  
Author(s):  
Andrei V. Afonin ◽  
Alexander V. Vashchenko ◽  
Mark V. Sigalov
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Critical Point ◽  
Intramolecular Hydrogen Bond ◽  
Bond Energy ◽  
Bond Critical Point ◽  
Hydrogen Bond Energy ◽  
H Nmr ◽  
Nmr Data ◽  
Intramolecular Hydrogen

Novel equations have been derived for the assessment of the E intramolecular hydrogen bond energy based on the experimental1H NMR data and the calculated QTAIM topologicalVandρparameters of the hydrogen bond critical point.

Characterization of the 2,2′-bipyridine chelates of lanthanum(III) in acetonitrile. A 1H, 13C, 17O, and 139La NMR study

1993 ◽  
Vol 71 (3) ◽  
pp. 377-383 ◽  
Author(s):  
Monique Fréchette
Keyword(s):  
Coordination Sphere ◽  
Chemical Shifts ◽  
Complexation Reaction ◽  
Complex Species ◽  
H Nmr ◽  
Nmr Data ◽  
Nmr Study ◽  
Close Proximity ◽  
Coordinated Water

We have investigated the reaction between La(NO3)3•6H2O and 2,2′-bipyridine (bipy) in acetonitrile by means of 139La, 17O, 13C, and 1H NMR spectroscopy. The 139La spectra show up to three different sites with variable intensities attributed to solvated La(III) ions and to two complex species with one or two bipy moieties in the La(III) coordination sphere. 17O NMR indicates that during the complexation reaction, the coordinated water is totally displaced from the coordination sphere whereas the nitrate groups remain coordinated. Proton NMR data confirm the water expulsion. In addition, the proton chemical shifts of bipy, in comparison with the 13C NMR data, clearly show an anisotropic shielding when two bipy are coordinated to La(III). Therefore, the two bipy molecules are in close proximity in the coordination sphere. From the NMR results it has been shown that, during the complexation process, five different La(III) species are formed: [La(NO3)3(CH3CN)4], [La(NO3)3(CH3CN)3(H2O)], [La(NO3)3(bipy)(CH3CN)2], [La(NO3)3(bipy)(CH3CN)-(H2O)], and [La(NO3)3(bipy)2]. Each La(III) complex has a coordination member of 10, with NO3− and bipy acting as chelating ligands. Furthermore, the structure of the La(NO3)3(bipy)2 complex in solution shows similarities with the solid state compound. Finally, comparisons are made with the La(III) complexes previously obtained with 1,10-phenanthroline.

Ab initio and 1H NMR study of the Zn(II) complexes of a nido- and a closo-carboranylporphyrin

2004 ◽  
Vol 08 (07) ◽  
pp. 996-1006 ◽  
Author(s):  
Petia Bobadova-Parvanova ◽  
Yuko Oku ◽  
Anura Wickramasinghe ◽  
Randall W. Hall ◽  
M. Graça H. Vicente
Keyword(s):  
Ab Initio ◽  
Complex Mixture ◽  
Neutron Capture Therapy ◽  
Ab Initio Study ◽  
Hydrogen Atoms ◽  
Pyridine Ligand ◽  
H Nmr ◽  
Boron Neutron Capture ◽  
Nmr Data ◽  
Nmr Study

An ab initio study of a promising nido-carboranylporphyrin for the boron neutron capture therapy of tumors, and of its closo precursor is reported. Base-induced deboronation of neutral ZnDCP , believed to exist as a mixture of 3 stereoisomers, produces the tetraanionic ZnDCP 4- as a complex mixture of isomers. 1 H NMR data and ab initio calculations support these findings. The position of the axial pyridine ligand in ZnDCP 4- and the orientation of the endo hydrogen atoms on the open faces of the nido-carborane cages significantly influence the total energy of the ZnDCP 4- structures. It is suggested that the "cocktail" of isomers possibly enhances the biological activity of tetra(nido-carboranyl)porphyrins, such as ZnDCP 4-.

scholarly journals 1H NMR studies distinguish the water soluble metabolomic profiles of untransformed and RAS-transformed cells

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2104 ◽  
Author(s):  
Vered Marks ◽  
Anisleidys Munoz ◽  
Priyamvada Rai ◽  
Jamie D. Walls
Keyword(s):  
Principal Component ◽  
Water Soluble ◽  
Lung Epithelial Cells ◽  
Transformed Cells ◽  
Nmr Studies ◽  
H Nmr ◽  
Metabolomic Profiling ◽  
Nmr Data ◽  
Lung Epithelial ◽  
Transformed Cell Lines

Metabolomic profiling is an increasingly important method for identifying potential biomarkers in cancer cells with a view towards improved diagnosis and treatment. Nuclear magnetic resonance (NMR) provides a potentially noninvasive means to accurately characterize differences in the metabolomic profiles of cells. In this work, we use1H NMR to measure the metabolomic profiles of water soluble metabolites extracted from isogenic control and oncogenic HRAS-, KRAS-, and NRAS-transduced BEAS2B lung epithelial cells to determine the robustness of NMR metabolomic profiling in detecting differences between the transformed cells and their untransformed counterparts as well as differences among the RAS-transformed cells. Unique metabolomic signatures between control and RAS-transformed cell lines as well as among the three RAS isoform-transformed lines were found by applying principal component analysis to the NMR data. This study provides a proof of principle demonstration that NMR-based metabolomic profiling can robustly distinguish untransformed and RAS-transformed cells as well as cells transformed with different RAS oncogenic isoforms. Thus, our data may potentially provide new diagnostic signatures for RAS-transformed cells.

1H NMR studies of proton transfer in Schiff base and carboxylic acid systems

1990 ◽  
Vol 68 (10) ◽  
pp. 1909-1916 ◽  
Author(s):  
Hoa Le-Thanh ◽  
D. Vocelle
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Hydrogen Bond ◽  
Schiff Base ◽  
Proton Transfer ◽  
Carboxylic Acids ◽  
Proton Nuclear Magnetic Resonance ◽  
Nmr Studies ◽  
H Nmr ◽  
Mineral Acids ◽  
Rapid Equilibrium

When the unconjugated Schiff base, isobutylidene isopropylamine (2), reacts with acids such as the mineral acids HCl, HBr, and HI, or the carboxylic acids trichloroacetic, monochloroacetic, and propionic acid, in CDCl3, several complexes are formed. In this study, 1H NMR allows us to differentiate between several possibilities. With the mineral acids, only 1:1 structures are seen and the chemical shift of the [Formula: see text] proton varies according to the strength of the hydrogen bond between the protonated Schiff base and its counterion. With the carboxylic acids, 1:1 and 1:2 structures are present in rapid equilibrium. In the presence of an excess of acid, protonation of the Schiff base increases considerably. Extrapolation of the results is given in terms of the molecular mechanism of vision. Keywords: protonation, proton nuclear magnetic resonance, proton transfer, rhodopsins, Schiff base.

Diethyl 2-Benzimidazol-1-ylsuccinate–Picric Acid (1/1) – An Inclusion Molecular Complex

1997 ◽  
Vol 53 (6) ◽  
pp. 961-967 ◽  
Author(s):  
P. Zaderenko ◽  
M. S. Gil ◽  
P. López ◽  
P. Ballesteros ◽  
I. Fonseca ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Molecular Complex ◽  
Picric Acid ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
H Nmr ◽  
Intramolecular Hydrogen ◽  
C Nmr

The crystal structure of the diethyl 2-benzimidazol-1-ylsuccinate–picric acid (1/1) molecular complex has been determined by X-ray diffraction analysis. Diethyl 2-benzimidazol-l-ylsuccinate molecules form channels along the a axis, in which the picric acid molecules are located. The benzimidazole moiety and the phenol group are held together by hydrogen bonding between the hydrogen of the phenol and the N3 atom of benzimidazole. Additionally, this hydrogen forms an intramolecular hydrogen bond with one O atom of the ortho-nitro group, thus producing a bifurcated hydrogen bond. 1H NMR spectra in DMSO-d 6 solution and CP/MAS solid 13 C NMR studies of this 2-benzimidazol-1-ylsuccinate–picric acid (1/1) molecular complex, as well as those of dimethyl, diethyl, di-n-butyl and 1-n-butyl-4-ethyl 2-imidazol-1-ylsuccinates, diethyl 2-pyrazol-1-ylsuccinate, ethyl imidazol-1-ylacetate, ethyl pyrazol-1-ylacetate and ethyl pyrazol-l-ylsuccinate, suggest that the picric acid linkage depends on the nature of the azole. Actual proton transfer is deduced for the imidazole derivatives, but only weak hydrogen bonding could be inferred for pyrazole derivatives.

Nmr Study in Sodium-Hydrogen-C60 Superconductor

1998 ◽  
Vol 513 ◽  
Author(s):  
H. Ogata ◽  
S. Miyajima ◽  
K. Imaeda ◽  
H. Inokuchi
Keyword(s):  
Quadrupole Coupling Constant ◽  
Peak Position ◽  
Coupling Constant ◽  
Nmr Studies ◽  
Nmr Spectrum ◽  
H Nmr ◽  
Nmr Study ◽  
First Order Phase Transition ◽  
Quadrupole Coupling ◽  
First Order Phase

ABSTRACT23Na and 1H NMR studies have been carried out for a NaxHyC60 superconductor The peak position of the 23Na NMR spectrum exhibits discontinuous upfield shift of 30 ppm at about 250 K, indicates a first order phase transition From the line shape of the 23Na spectrum obtained at 7 K, the quadrupole coupling constant tensor is evaluated to be |e2Qq/h|=3.7 MHz with the asymmetry parameter η = 0.95. The 1H NMR spectrum suggests an anionic hydrogen state with weakly delocalized nature.

A 1 H-NMR study of the solution conformation of secretin resonance assignment and secondary structure

FEBS Letters ◽  
1987 ◽  
Vol 215 (1) ◽  
pp. 88-94 ◽  
Author(s):  
Angela M. Gronenborn ◽  
Gunter Bovermann ◽  
G.Marius Clore
Keyword(s):  
Secondary Structure ◽  
Resonance Assignment ◽  
Solution Conformation ◽  
H Nmr ◽  
Nmr Study

Identification of acyl groups occurring in sesquiterpene lactones: Proton and carbon-13 NMR study

1987 ◽  
Vol 52 (2) ◽  
pp. 453-475 ◽  
Author(s):  
Miloš Buděšínský ◽  
David Šaman
Keyword(s):  
Chemical Shifts ◽  
Sesquiterpene Lactones ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Nmr Parameters ◽  
Nmr Data ◽  
Nmr Study ◽  
C Nmr

Characteristic 1H NMR parameters of 88 acyl groups, hitherto found as ester substituents in natural sesquiterpenic lactones, were determined from the measured spectra as well as literature data. Characteristic 13C NMR chemical shifts for 45 acyl groups were obtained in the same way; for the remaining acyls with hitherto unknown 13C NMR data the values were calculated on the basis of semiempirical relationships.

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