1 research outputs found
Amplified Vibrational Circular Dichroism as a Probe of Local Biomolecular Structure
We
show that the VCD signal intensities of amino acids and oligopeptides
can be enhanced by up to 2 orders of magnitude by coupling them to
a paramagnetic metal ion. If the redox state of the metal ion is changed
from paramagnetic to diamagnetic the VCD amplification vanishes completely.
From this observation and from complementary quantum-chemical calculations
we conclude that the observed VCD amplification finds its origin in
vibronic coupling with low-lying electronic states. We find that the
enhancement factor is strongly mode dependent and that it is determined
by the distance between the oscillator and the paramagnetic metal
ion. This localized character of the VCD amplification provides a
unique tool to specifically probe the local structure surrounding
a paramagnetic ion and to zoom in on such local structure within larger
biomolecular systems