Article Abstract:
Studies done on the interactions between amide groups in a bridged cyclic diamide, diazabicyclo[2.2.2]octane-3,6-dione, through the measurement of its infrared (IR) and ultra-violet (UV) absorption and electronic CD spectra and through ab initio calculations of its electronic structure is reported. Electronic CD spectrum arises from n pi* and pi(sub nb)pi* transitions that can be considered to be localized on one amide group, while charge-transfer transitions does not make a vital contribution to the electronic CD spectrum.
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Article Abstract:
The vacuum ultraviolet (UV) circular dichroism (CD) spectra of proteins are calculated by using synchrotron radiation CD (SRCD) spectra and X-ray crystal structures. The analysis of the effect of the conformation on charge-transfer transitions has shown that the n -> [pi]* charge-transfer transitions are vital in [alpha]-helical proteins, whereas in [beta] strand proteins the [pi] -> [pi]* charge-transfer transitions along the chain in the amino- to carboxy-end direction is dominant.
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Article Abstract:
The time-dependent density functional theory (TDDFT) is applied to study the valence pi-pi excited states of the tryptophan chromophores in the environment of the proteins barnase and human serum albumin. The computational techniques for determining the effects of environmental parameters on the electronic transitions at sites of interest within proteins are described.
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