Biomedical Engineering Reference
In-Depth Information
1100
fit 7
fit 6
fit 5
fit 4
fit 3
fit 2
fit 1
1000
900
800
700
600
500
400
fit 6
300
fit 5
fit 4
fit 3
fit 2
fit 1
200
100
0
2
3
4
5
6
7
8
9
10
11
12
13
In (
r
)
FIGURE 5.9
Bell-Evans plot. Experimental plot showing multiple fits obtained from
antibody-uranyl chelator complexes (Odorico et al. 2007a). The two loading rate regimes
are clearly visible: one at low loading rates from 44 to 200 pN/s and one at high loading rates
from 3641 to 242,802 pN/s. Using various antibodies and different metals, it was shown that
the low loading rate regime depicts the rupture between the antibody and the metal, whereas
the high loading rate regime depicts the rupture between the antibody and the metal-chelator
(Teulon et al. 2008).
2011). In the case of two loading rate regimes, an inner energy barrier is crossed
out first followed by a second outer energy barrier (Yuan et al. 2000). The formal-
ism of Evans (Evans & Ritchie, 1997) explains that by applying a linear force on
a bond, the energy landscape is tilted such that the outer energy barrier is reduced.
Consequently, when present the inner energy barrier can be observed by applying
high loading rates.
5.9 MULTIPLE PARALLEL UNBINDING IN BELL-EVANS PLOTS
The presence of multiple parallel unbinding events is first observed in the distribution
of rupture forces with the presence of multiple Gaussian fits (Figure 5.10a). Early
single molecule force spectroscopy studies with AFM identified this distribution as
quanta of forces (Florin et al. 1994). This has been widely verified since then. Now,
this appears as a difficulty for DFS treatment since at a given loading rate we obtained
not only one but two or more most probable rupture forces. Consequently, the Bell-
Search WWH ::
Custom Search