Heteronuclear relayed E.COSY applied to the determination of accurate 3J(HN,C?) and 3J(H?,C?) coupling constants in Desulfovibrio vulgaris flavodoxin

1996 ◽  
Vol 7 (2) ◽  
Author(s):  
J�rgenM. Schmidt ◽  
Frank L�hr ◽  
Heinz R�terjans
Keyword(s):  
Coupling Constants ◽  
Desulfovibrio Vulgaris ◽  
Desulfovibrio Vulgaris Flavodoxin

Computational approaches to amino acid side-chain conformation using combined NMR theoretical and experimental results: leucine-67 in Desulfovibrio vulgaris flavodoxin

2021 ◽  
Author(s):  
Jesús San Fabián ◽  
Salama Omar ◽  
José Manuel García de la Vega
Keyword(s):  
Amino Acid ◽  
Dynamic Effect ◽  
Experimental Results ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Side Chain ◽  
Desulfovibrio Vulgaris ◽  
Amino Acid Side Chain ◽  
Desulfovibrio Vulgaris Flavodoxin ◽  
Torsional Angles

Abstract In this paper, we show that the combination of NMR theoretical and experimental results can help to solve the molecular structure of peptides, here it is used as an example the residue Leucine-67 in Desulfovibrio vulgaris flavodoxin. We apply a computational protocol based on the leucine amino acid dipeptide, which, using calculated and experimental spin–spin coupling constants, allows us to obtain the conformation of the amino acid side chain. Calculated results show that the best agreement is obtained when three conformers around the lateral chain angle $\chi _1$ are considered or when the dynamic effect in the torsional angles is included. The population of each structure is estimated and analyzed according to the correlation between those two approaches. Independently of the approach, the estimated $\chi _1$ angle in solution is close to the staggered value of -60$^\circ $ and deviates significantly from the average x-ray angle of -90$^\circ $.

$\mathit{Ab\!-\!initio}$ Determination of Magnetic Interface Coupling Constants for Magnetic Multilayers

1997 ◽  
Vol 7 (11) ◽  
pp. 1299-1304 ◽  
Author(s):  
P. Weinberger ◽  
C. Sommers ◽  
U. Pustogowa ◽  
L. Szunyogh ◽  
B. Újfalussy
Keyword(s):  
Ab Initio ◽  
Magnetic Multilayers ◽  
Coupling Constants ◽  
Interface Coupling

Gradient-Enhanced Inverse-Detected NMR Techniquesfor Determination of 1H-15N Coupling Constants in 2,2-Dimethylpenta-3,4-dienal Derivatives

1997 ◽  
Vol 62 (11) ◽  
pp. 1747-1753 ◽  
Author(s):  
Radek Marek
Keyword(s):  
Double Bond ◽  
Chemical Shifts ◽  
Multiple Bond ◽  
Coupling Constants ◽  
Single Quantum ◽  
Nmr Techniques ◽  
Phase Sensitive ◽  
Heteronuclear Coupling

Determination of 15N chemical shifts and heteronuclear coupling constants of substituted 2,2-dimethylpenta-3,4-dienal hydrazones is presented. The chemical shifts were determined by gradient-enhanced inverse-detected NMR techniques and 1H-15N coupling constants were extracted from phase-sensitive gradient-enhanced single-quantum multiple bond correlation experiments. Stereospecific behaviour of the coupling constants 2J(1H,15N) and 1J(1H,13C) has been used to determine the configuration on a C=N double bond. The above-mentioned compounds exist predominantly as E isomers in deuteriochloroform.

21,22-Disubstituted 18α,19βH-Ursane Derivatives with Oxabicyclooctane System in Ring E

1993 ◽  
Vol 58 (1) ◽  
pp. 173-190 ◽  
Author(s):  
Eva Klinotová ◽  
Jiří Klinot ◽  
Václav Křeček ◽  
Miloš Buděšínský ◽  
Bohumil Máca
Keyword(s):  
Spectral Data ◽  
Spin Systems ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Nmr Spectrum ◽  
Proton Proton ◽  
H Nmr ◽  
Proton Coupling ◽  
C Nmr

Reaction of 3β-acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) and 20β,28-epoxy-21,22-dioxo-19α,19βH-ursan-3β-yl acetate (IIIb) with diazomethane afforded derivatives XII-XIV with spiroepoxide group in position 21 or 22, which were further converted into hydroxy derivatives XV and XVII. Ethylene ketals VIII-X were also prepared. In connection with the determination of position and configuration of the functional groups at C(21) and C(22), the 1H and 13C NMR spectral data of the prepared compounds are discussed. Complete analysis of two four-spin systems in the 1H NMR spectrum of bisethylenedioxy derivative Xb led to the proton-proton coupling constants from which the structure with two 1,4-dioxane rings condensed with ring E, and their conformation, was derived.

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