Ew. Schlag et al., Charge conductivity in peptides: Dynamic simulations of a bifunctional model supporting experimental data, P NAS US, 97(3), 2000, pp. 1068-1072
Citations number
28
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Our previous finding and the given mechanism of charge and electron transfe
r in polypeptides are here integrated in a bifunctional model involving ele
ctronic charge transfer coupled to special internal rotations. Present mole
cular dynamics simulations that describe these motions in the chain result
in the mean first passage times for the hopping process of an individual st
ep. This "rest and fire" mechanism is formulated in detail-i.e., individual
amino acids are weakly coupled and must first undergo alignment to reach t
he special strong coupling. This bifunctional model contains the essential
features demanded by our prior experiments, The molecular dynamics results
yield a mean first passage time distribution peaked at about 140 fs, in clo
se agreement with our direct femtosecond measurements. In logic gate langua
ge this is a strongly conducting ON state resulting from small firing energ
ies, the system otherwise being a quiescent OFF state. The observed time sc
ale of about 200 fs provides confirmation of our simulations of transport,
a model of extreme transduction efficiency. It explains the high efficiency
of charge transport observed in polypeptides. We contend that the moderate
speed of weak coupling is required in our model by the bifunctionality of
peptides. This bifunctional mechanism agrees with our data and contains val
uable features for a general model of long-range conductivity, final reacti
vity, and binding at a long distance.