Vibrational Circular Dichroism and IR Absorption Spectra of Amino Acids: A Density Functional Study

2010 ◽  
Vol 114 (10) ◽  
pp. 3591-3601 ◽  
Author(s):  
Zhi Ji ◽  
Rubén Santamaria ◽  
Ignacio L. Garzón
Keyword(s):  
Amino Acids ◽  
Circular Dichroism ◽  
Absorption Spectra ◽  
Density Functional ◽  
Vibrational Circular Dichroism ◽  
Functional Study ◽  
Ir Absorption ◽  
Density Functional Study ◽  
Ir Absorption Spectra ◽  
Circular Dichroïsm

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>

Vibrational circular dichroism and IR absorption of DNA complexes with Cu2+ ions

Biopolymers ◽  
2003 ◽  
Vol 72 (5) ◽  
pp. 374-390 ◽  
Author(s):  
V. Andrushchenko ◽  
J. H. Van De Sande ◽  
H. Wieser
Keyword(s):  
Circular Dichroism ◽  
Vibrational Circular Dichroism ◽  
Ir Absorption ◽  
Dna Complexes ◽  
Circular Dichroïsm
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