Circular dichroism and Cotton effects in the near-ultraviolet spectral region of aldolase

1967 ◽  
Vol 133 (2) ◽  
pp. 366-369 ◽  
Author(s):  
K.R. Leonard ◽  
I.O. Walker
Keyword(s):  
Circular Dichroism ◽  
Spectral Region ◽  
Near Ultraviolet ◽  
Cotton Effects ◽  
Ultraviolet Spectral Region ◽  
Circular Dichroïsm

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.

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.

Circular dichroism spectra of amino acid complexes. II. Chelated amino acid complexes with the CoN5O chromophore

1970 ◽  
Vol 23 (9) ◽  
pp. 1735 ◽  
Author(s):  
CJ Hawkins ◽  
PJ Lawson
Keyword(s):  
Amino Acids ◽  
Circular Dichroism ◽  
Amino Acid ◽  
Visible Region ◽  
Optically Active ◽  
Circular Dichroism Spectra ◽  
Amino Acid Complexes ◽  
Similar Series ◽  
Cotton Effects ◽  
Circular Dichroïsm

The circular dichroism spectra of a series of optically active (α-aminocarboxylato)tetraamminecobalt(111) complexes have been measured in aqueous solution, and in the presence of salts of polarizable anions. The observed spectra in the visible region have been analysed to determine the signs of the Cotton effects of the three components of the 1A1g ↔ 1T1g cobalt(111) transition. For L-amino acids, the transition with A2g(D4h) parentage is negative, and the two transitions with Eg(D4h) parentage have opposite signs. Published circular dichroism spectra of complexes of the type [Co(en)2(L-am)]2+ were similarly interpreted in terms of a perturbed tetragonal chromophore, and it was shown that the vicinal effect of the L-amino acids imposed the same signs onto the component transitions as for the tetraammines and for a similar series of pentaamminecobalt(111) complexes.

Circular Dichroism of C-Phycoerythrin: A Conformational Analysis

1980 ◽  
Vol 35 (5-6) ◽  
pp. 367-375 ◽  
Author(s):  
Elisabeth Langer ◽  
Harald Lehner ◽  
Wolfhart Rüdiger ◽  
Barbara Zickendraht-Wendelstadt
Keyword(s):  
Circular Dichroism ◽  
Secondary Structure ◽  
Conformational Changes ◽  
Spectral Region ◽  
Protein Unfolding ◽  
Extensive Study ◽  
Random Coil ◽  
Linear Superposition ◽  
Thermally Induced ◽  
Circular Dichroïsm

Abstract An extensive study of the chiroptical properties of C-phycoerythrin and the α-and β-subunits in the spectral region from 700 -200 nm is presented. Based on the VIS-circular dichroism inherently chiral conform ations are proposed for the co­ valently linked chromophores. By means of mean residue ellipticities and the experimental circular dichroism spectra in the region of the n → π* peptide transition the a-helix contents of the apoproteins of the ac-and ß-subunits are estimated to amount to 60% and 40%, respectively. The circular dichroism spectrum of native C-phycoerythrin is congruent with a linear superposition of the α-and β-subspectra, in the whole spectral region studied. Since a-and β-subunits are associated in native C-phycoery-thrin as revealed by sedim entation analysis the interactions between the subunits in the native chromoprotein are not accom panied by substantial conform ational changes. In the temperature range 0°-40°C the thermally induced changes of the chrom ophores in native C-phycoerythrin are not associated with changes of the secondary structure of the apoprotein. Unfolding occurs at 60°-70°C but slowly leads to irreversible denaturation. Protein unfolding starts at 3 M urea. The random coil secondary structure of the apoproteins is reached at 8 M urea. At this concentration the absorbance and the optical activity of the chrom o­ phores are reduced by a factor 3 and 10, respectively. The conformational changes in the peptide with increasing denaturant concentration are not synchronous with those induced in the Chromo­ phore indicating that a m ultistep process is operative during unfolding. The C D results on dena­ turation are supplem ented by absorption and em ission spectroscopy.

Characterization of a ribonuclease S refolding intermediate

1993 ◽  
Vol 345 (1674) ◽  
pp. 131-140
Keyword(s):  
Circular Dichroism ◽  
Cd Spectrum ◽  
Near Ultraviolet ◽  
Circular Dichroïsm

D uring ribonuclease S (RN ase S) refolding, two peptide fragm ents recognize each other, and bind to g eth er to form a refolding in term ediate which slowly converts to th e nativ e state. We have characterized this refolding interm ediate using absorbance, circular dichroism (CD), and nuclear m agnetic resonance (NMR) spectroscopies. These techniques reveal significant am ounts of bo th secondary and te rtia ry stru ctu re ; the in term ediate differs from a m olten globule in being packed and native-like, b u t it resembles a m olten globule in having no near-ultraviolet (UV) CD spectrum . Final refolding is slow and accom panies proline isom erization. The results show th a t a t least two separate stages are observed in the form ation of the te rtia ry stru ctu re of RNaseS.

scholarly journals Applied Circular Dichroism: A Facile Spectroscopic Tool for Configurational Assignment and Determination of Enantiopurity

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Macduff O. Okuom ◽  
Raychelle Burks ◽  
Crysta Naylor ◽  
Andrea E. Holmes
Keyword(s):  
Circular Dichroism ◽  
High Performance ◽  
Maximum Amplitude ◽  
Qualitative Evaluation ◽  
Racemic Mixture ◽  
Good Tool ◽  
Configurational Assignment ◽  
Cotton Effects ◽  
Spectroscopic Tool ◽  
Circular Dichroïsm

In order to determine if electronic circular dichroism (ECD) is a good tool for the qualitative evaluation of absolute configuration and enantiopurity in the absence of chiral high performance liquid chromatography (HPLC), ECD studies were performed on several prescriptions and over-the-counter drugs. Cotton effects (CE) were observed for both S and R isomers between 200 and 300 nm. For the drugs examined in this study, the S isomers showed a negative CE, while the R isomers displayed a positive CE. The ECD spectra of both enantiomers were nearly mirror images, with the amplitude proportional to the enantiopurity. Plotting the differential extinction coefficient (Δε) versus enantiopurity at the wavelength of maximum amplitude yielded linear standard curves with coefficients of determination (R2) greater than 97% for both isomers in all cases. As expected, Equate, Advil, and Motrin, each containing a racemic mixture of ibuprofen, yielded no chiroptical signal. ECD spectra of Suphedrine and Sudafed revealed that each of them is rich in 1S,2S-pseudoephedrine, while the analysis of Equate vapor inhaler is rich in R-methamphetamine.

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