Biomedical Engineering Reference
In-Depth Information
Fig. 1.38
Manipulating the
peptide with charged residues
inside a water-filled nanotube
(i.e., System II). The
x
-coordinate of the center of
mass of the Aˇ
16-22
peptide
(
red line
) as a function of
time, together with the
x
-coordinate of the
geometrical center of the
external charges (
black line
)
(reprinted from [
42
].
Copyright 2009 American
Chemical Society)
Fig. 1.39
Electrostatic
interaction energy of the
external charges with the
Aˇ
16-22
peptide and with the
deprotonated carboxyl group
(COO) as a function of
simulation time
COO group and the external charges. Numerically, we have found that the average
electrostatic interaction energy of the external charges with the COO group is
973
˙
143 kJ/mol, quite close to the electrostatic interaction energy of the external
charges with the peptide (see also Fig.
1.39
). Likewise, the distances between the
COM of the COO group and the geometrical center of the external charge range
from 0.6 to 2.2 nm with an average value of 0.8 nm. These distances are smaller
than the distances between the COM of the peptide and the geometrical center of
the external charges. Consequently, the manipulation of the peptide mainly results
from the tight trapping of the COO group by the external charges.
We have also calculated the electrostatic forces that the peptide and water inside
the nanochannel exert on the external charges along the
x
-axis. The forces range
from
600 to
C
600 pN (see Fig.
1.40
), which also fall within the working ranges
of many existing techniques such as STM and AFM.
The number of the charges in the externally charged group is important for the
manipulation. We have found only one successful case in five simulations with
