An extended theoretical formulation of the circular dichroism band shape of chromophore aggregates by use of the ensemble‐averaged resolvent matrix method

1987 ◽  
Vol 86 (10) ◽  
pp. 5308-5314 ◽  
Author(s):  
Mamoru Kamiya
Keyword(s):  
Circular Dichroism ◽  
Matrix Method ◽  
Resolvent Matrix ◽  
Band Shape ◽  
Theoretical Formulation ◽  
Circular Dichroism Band ◽  
Circular Dichroïsm

A Solution to the Artifact Problem in Fourier Transform Vibrational Circular Dichroism

1988 ◽  
Vol 42 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Petr Malon ◽  
Timothy A. Keiderling
Keyword(s):  
Fourier Transform ◽  
Circular Dichroism ◽  
Vibrational Circular Dichroism ◽  
Band Shape ◽  
Ft Ir ◽  
Circular Dichroïsm

Using a newly constructed FT-IR vibrational circular dichroism (VCD) instrument, we have found that elimination of the ellipsoidal collection mirror before the detector and its replacement by a lens leads to a significant improvement in the absorption artifact problem seen previously in FT-IR/VCD. In the mid-IR region, we have been able to measure VCD of a single enantiomer for molecules such as α-pinene, 3-methylcyclohexanone, and dimethyltartrate. More importantly, this reduction in artifact level brings the FT-IR/VCD band shape of some particularly-difficult-to-measure bands, such as carbonyl stretches, into better agreement with those found in dispersive measurements. These results imply that the dispersive results are reliable, though of lower resolution than those obtained with the use of FT-IR/VCD.

Vibronic structure in the far-UV electronic circular dichroism spectra of proteins

2015 ◽  
Vol 177 ◽  
pp. 329-344 ◽  
Author(s):  
Zhuo Li ◽  
David Robinson ◽  
Jonathan D. Hirst
Keyword(s):  
Circular Dichroism ◽  
Matrix Method ◽  
Vibrational Structure ◽  
Cd Spectra ◽  
Peptide Backbone ◽  
Electronic Circular Dichroism ◽  
Vibronic Structure ◽  
Far Ultraviolet ◽  
High Level ◽  
Circular Dichroïsm

The Franck–Condon effect is considered and the vibrational structure of the πnbπ* transition of the peptide backbone is incorporated into matrix method calculations of the electronic circular dichroism (CD) spectra of proteins in the far-ultraviolet. We employ the state-averaged CASPT2 method to calculate the ground and πnbπ* excited state geometries and frequencies of N-methylacetamide (NMA), which represents the peptide chromophore. The results of these calculations are used to incorporate vibronic levels of the excited states into the matrix method calculation. The CD spectra of a set of 49 proteins, comprising a range of structural types, are calculated to assess the influence of the vibrational structure. The calculated spectra of α-helical proteins are better resolved using the vibronic parameters and correlation between the experimental and the calculated intensity of less regular β structure proteins improves over most wavelengths in the far-UV. No obvious improvement is observed in the calculated spectra of regular β-sheet proteins. Our high-level ab initio calculations of the vibronic structure of the πnbπ* transition in NMA have provided some further insight into the physical origins of the nature of protein CD spectra in the far-UV.

Origin of the positive 225–230 nm circular dichroism band in proteins

1988 ◽  
Vol 31 (1-2) ◽  
pp. 45-51 ◽  
Author(s):  
R.C. Hider ◽  
G. Kupryszewski ◽  
P. Rekowski ◽  
B. Lammek
Keyword(s):  
Circular Dichroism ◽  
Circular Dichroism Band ◽  
Circular Dichroïsm
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