Conformation of 3-acetamido-3,6-dideoxyhexopyranosides: Circular dichroism study

1979 ◽  
Vol 44 (1) ◽  
pp. 174-182 ◽  
Author(s):  
Slavomír Bystrický ◽  
Ivo Frič ◽  
Jan Staněk ◽  
Karel Čapek ◽  
Jiří Jarý ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Spatial Orientation ◽  
Amide Group ◽  
Cd Spectra ◽  
Pyranose Ring ◽  
Cotton Effects ◽  
Circular Dichroïsm

CD spectra of 15 stereoisomeric methyl 3-acetamido-3,6-dideoxyhexopyranosides were measured in methanol, 2,2,2-trifluoroethanol and acetonitrile. The data have been applied for estimation of probable conformations. The factor determining signs of the observed Cotton effects seems to be the spatial orientation of the acetamido group with respect to the pyranose ring. The possible role of a non-planar amide group is also discussed.

Circulardichroismusuntersuchungen von Polyalkohol- und Zucker-Vanadat(V)-Komplexen / Circular Dichroism Studies of Polyalcohol and Sugar Vanadate(V) Complexes

1989 ◽  
Vol 44 (11) ◽  
pp. 1464-1472 ◽  
Author(s):  
Hermann Bauer ◽  
Jeanine Brun ◽  
Alexius R. Hernanto ◽  
Wolfgang Voelter ◽  
Spyridon Paraskewas
Keyword(s):  
Circular Dichroism ◽  
Wavelength Range ◽  
Optically Active ◽  
Hydroxyl Groups ◽  
Pyranose Ring ◽  
Cotton Effects ◽  
Circular Dichroïsm

The complexes of tetravanadate ions with optically active polyols and carbohydrates with suitable steric properties show up to four separate cotton effects in the wavelength range of λ = 200-350 nm. Thus it is possible to classify pyranoses into four groups according to their circular dichroitic behaviour and determine the configuration and the conformation of the hydroxyl groups attached to the pyranose ring.

scholarly journals Messung und Berechnung der CD-Spektren der Biaryl-Alkaloide Ancistrocladein und Dioncophyllein A [1] / Detection and Calculation of the CD Spectra from the Biaryl Alkaloids Ancistrocladeine and Dioncophylleine A [1]

1993 ◽  
Vol 48 (2) ◽  
pp. 140-148 ◽  
Author(s):  
J. Fleischhauer ◽  
A. Koslowski ◽  
B. Kramer ◽  
E. Zobel ◽  
G. Bringmann ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Cd Spectra ◽  
Circular Dichroïsm

AbstractThe circular dichroism (CD) of the biaryls ancistrocladeine and dioncophylleine A has been studied. The CNDO/S method in combination with a Boltzmann weighting o f different structures using AM 1 energies has been applied to reproduce the experimental CD spectra o f the two alkaloids with known absolute configuration at with those o f the exciton chirality method.

Circular dichroism spectra of tetraamminecobalt(III) complexes of amino alcohols

1978 ◽  
Vol 31 (11) ◽  
pp. 2399 ◽  
Author(s):  
CJ Hawkins ◽  
GA Lawrance ◽  
JA Palmer
Keyword(s):  
Circular Dichroism ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Amino Alcohols ◽  
Circular Dichroism Spectra ◽  
Chemical Shift Difference ◽  
Solvent Dependence ◽  
Cotton Effects ◽  
Circular Dichroïsm ◽  
Chiral Amino Alcohols

The circular dichroism spectra are reported for tetraamminecobalt(III) complexes with the chiral amino alcohols 2-aminopropan-1-ol, 2- aminobutan-1-ol, 1-aminopropan-2-ol, 2-amino-1-phenyl-ethanol, ψ- ephedrine and ephedrine with the alcohol groups protonated (OH) and deprotonated (O-). The solvent dependence of the chemical shifts of the NH protons was investigated to determine the effects of stereoselective solvation on the circular dichroism, but, in contrast to some other related systems, the chemical shift difference between the two NH2 protons was relatively insensitive to solvent. Consistent with this, the circular dichroism spectra of the tetraphenylborate salts of the deprotonated complexes were found not to be markedly dependent on solvent. Tetraammine-{(-)-ψ-ephedrine)cobalt(III) and tetraammine{(-)- ephedrine}cobalt(III) were found to have the same signs of Cotton effects for the various d-d transitions, whereas bis{(-)-ψ- ephedrine}copper(II) and bis{(-)-ephedrine}copper(II) had opposite signs. This has been explained in terms of different conformer populations in the cobalt(III) and copper(II) systems.

Circular dichroism of benzylidene derivatives of glycerol and mannitol

1977 ◽  
Vol 30 (11) ◽  
pp. 2465 ◽  
Author(s):  
RM Carman ◽  
CJ Hawkins ◽  
JJ Kibby
Keyword(s):  
Circular Dichroism ◽  
Ring Systems ◽  
Cotton Effects ◽  
Derivatives Of ◽  
Circular Dichroïsm

The c.d. spectra are reported for a series of benzylidene derivatives of glycerol and mannitol containing 1,3-dioxolan, 1,3-dioxan and 1,3- dioxepan ring systems. The signs of the Cotton effects of 1Lb and 1La transitions of the phenyl chromophore have been rationalized in terms of recently proposed sector rules for these transitions.

A β-cyclodextrin–resveratrol inclusion complex and the role of geometrical and electronic effects on its electronic induced circular dichroism

RSC Advances ◽  
2013 ◽  
Vol 3 (26) ◽  
pp. 10242 ◽  
Author(s):  
Eduardo Troche-Pesqueira ◽  
Ignacio Pérez-Juste ◽  
Armando Navarro-Vázquez ◽  
María Magdalena Cid
Keyword(s):  
Circular Dichroism ◽  
Inclusion Complex ◽  
Induced Circular Dichroism ◽  
Electronic Effects ◽  
Circular Dichroïsm

The important role of non-covalent interactions for the vibrational circular dichroism of lactic acid in aqueous solution

2021 ◽  
Author(s):  
Sascha Jähnigen ◽  
Daniel Sebastiani ◽  
Rodolphe Vuilleumier
Keyword(s):  
Lactic Acid ◽  
Circular Dichroism ◽  
Computational Study ◽  
Bulk Water ◽  
Vibrational Circular Dichroism ◽  
Ab Initio Molecular Dynamics ◽  
Non Covalent Interactions ◽  
Circular Dichroïsm ◽  
Covalent Interactions

We present a computational study of vibrational circular dichroism (VCD) in solutions of (S)-lactic acid, relying on ab initio molecular dynamics (AIMD) and full solvation with bulk water. We discuss...

Citrate chelation as a potential mechanism against aluminum toxicity in cells: the role of calmodulin

1985 ◽  
Vol 63 (11) ◽  
pp. 1167-1175 ◽  
Author(s):  
Charles G. Suhayda ◽  
Alfred Haug
Keyword(s):  
Circular Dichroism ◽  
Conceptual Understanding ◽  
Aluminum Toxicity ◽  
Hydrophobic Surface ◽  
Native Structure ◽  
Calcium Calmodulin Dependent ◽  
Α Helix ◽  
Kinetics Of ◽  
Circular Dichroïsm

At a molar excess of [citrate]/[aluminum], this organic acid can protect calmodulin from aluminum binding if the metal is presented to the protein in stoichiometric micromolar quantities, as judged by fluorescence and circular dichroism spectroscopy. Similar citrate concentrations are also capable of fully restoring calmodulin's hydrophobic surface exposure to that of the native protein when calmodulin was initially damaged by aluminum binding. Fluoride anions are equally effective in restoring calmodulin's native structure as determined by fluorescence spectroscopy. Measurements of the kinetics of citrate-mediated aluminum removal also indicated that the metal ions are completely removed from calmodulin, consistent with results derived from atomic absorption experiments. On the other hand, results from circular dichroism studies indicated that citrate-mediated aluminum removal from calmodulin can only partially restore the α-helix content to that originally present in apocalmodulin or in calcium–calmodulin, dependent upon the absence or presence of calcium ions. The results that chelators like citrate can protect calmodulin from aluminum injury may provide a conceptual understanding of physiological observations regarding aluminum-tolerant plant species which are generally rich in certain organic acids.

scholarly journals Water-Mediated Electronic Structure of Oligopeptides Probed by Their UV Circular Dichroism, Absorption Spectra, and Time-Dependent DFT Calculations

2020 ◽  
Author(s):  
Anshuman Kumar ◽  
Siobhan E. Toal ◽  
David DiGuiseppi ◽  
Reinhard Schweitzer-Stenner ◽  
Bryan Wong
Keyword(s):  
Circular Dichroism ◽  
Absorption Spectra ◽  
Density Functional ◽  
Time Dependent ◽  
Water Model ◽  
Cd Spectra ◽  
Influence Of Water ◽  
Explicit Consideration ◽  
A Charge ◽  
Circular Dichroïsm

<p>We investigate the UV absorption spectra of a series of cationic GxG (where x denotes a guest residue) peptides in aqueous solution and find that the spectra of a subset of peptides with x = A, L, I, K, N, and R (and, to a lesser extent, peptides with x = D and V) vary as a function of temperature. To explore whether or not this observation reflects conformational dependencies, we carry out time-dependent density functional calculations for the polyproline II (pPII) and β-strand conformations of a limited set of tripeptides (x = A, V, I, L, and R) in implicit and explicit water. We find that the calculated CD spectra for pPII can qualitatively account for the experimental spectra irrespective of the water model. The reproduction of the <i>β</i>-strand UV-CD spectra, however, requires the explicit consideration of water. Based on the calculated absorption spectra, we explain the observed temperature dependence of the experimental spectra as being caused by a reduced dispersion (larger spectral density) of the overlapping NV<sub>2</sub> band and the influence of water on electronic transitions in the β-strand conformation. Contrary to conventional wisdom, we find that both the NV<sub>1</sub> and NV<sub>2</sub> band are the envelopes of contributions from multiple transitions that involve more than just the HOMOs and LUMOs of the peptide groups. A natural transition orbital analysis reveals that some of the transitions with significant oscillator strength have a charge-transfer character. The overall manifold of transitions, in conjunction with their strengths and characters, depends on the peptide’s backbone conformation, peptide hydration, and also on the side chain of the guest residue. It is particularly noteworthy that molecular orbitals of water contribute significantly to transitions in <i>β</i>-strand conformations. Our results reveal that peptide groups, side chains, and hydration shells must be considered as an entity for a physically valid characterization of UV absorbance and circular dichroism. </p>

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