INVESTIGADORES
MURGIDA Daniel Horacio
congresos y reuniones científicas
Título:
Electric field effects on the structure, function and dynamics of redox proteins
Autor/es:
MURGIDA, D. H.
Lugar:
La Plata
Reunión:
Conferencia; Humboldt Kolleg - International Conference on Physics; 2011
Resumen:
Most of the
biochemical and biophysical processes of redox proteins take place at membranes
and thus under the influence of strong local electric fields which are likely
to affect the structure as well as the reaction mechanism and dynamics. To
analyse such electric field effects we have employed biomimetic interfaces for
protein attachment that consist of membrane models deposited on nanostructured
metal electrodes. For such devices, surface enhanced resonance Raman and
infrared absorption spectroscopy are powerful techniques to disentangle the
complex interfacial processes of proteins in terms of rotational diffusion,
electron transfer, as well as protein and cofactor structural changes. The atomistic interpretation of
the experiments is guided by molecular dynamics (MD) simulations and electron
pathways calculations of the biomimetic complexes. Using
this approach we have investigated a variety of heme soluble proteins (cyt-c; cyt-b562,
cyt-c6, iso-cyt-c) that act as electron shuttles in photosynthetic
and respiratory chains of different organisms, as well as membrane terminal
respiratory enzymes.
In general terms it is concluded that the
overall ET rates are determined by the interplay of protein dynamics and tunnelling
probabilities at the different conformations along the dynamics, which in turn
is strongly modulated by the local electric field. It is also shown that
sufficiently strong electric fields are able to induce reversible structural
changes of the proteins, affecting thermodynamic and kinetic parameters of the
ET reactions. Based on these results it is hypothesized that transmembrane
potentials play a regulatory role in respiration and photosynthesis via a
feedback inhibition mechanism.
In addition, it is
shown that electric field effects may be functional for the switch from the
redox to the peroxidase function of cytochrome c, one of the key events in programmed cellular death.