Biomedical Engineering Reference
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(a)
long-time trace
5 s
(b)
short-time trace
0.02 s
(c)
nc
3.0x10
-9
0
2.0x10
-9
1.0x10
-9
1
2
3
0.0
0
100
200
300
400
Current / pA
Fig. 5.11
Alamethicin channel activity in a 1,2-Dioleoyl-sn-Glycero-3-Phosphocholine (
DC
18
:
1
PC
)/n-decane bilayer.
a
and
b
, long- (30 s) and short- (0.1 s) time records, respectively, of current
traces through alamethicin channels.
c
current level histograms obtained from 30 s traces.
N
i
is
the point count at any value of current
and
i
N
i
10
6
(
≥
0pA
)
=
N
tot
(
=
2
×
)
is the total point
count during the whole record time. Sum of the probabilities
(
W
nc
+
W
0
+
W
1
+
W
2
+
W
3
+
...)
10
−
4
,
is 1.0
(
W
i
=
N
i
/
N
tot
)
in the point count plots.
W
nc
,
W
0
,
W
1
,
W
2
,
W
3
, etc. are 9809
.
19
×
10
−
4
,42
10
−
4
,12
10
−
4
,1
10
−
4
, etc. respectively. Current levels 0, 1,
134
.
43
×
.
305
×
.
39
×
.
68
×
2, and 3 are at 29
6are
the numbers of current traces collected at independent experimental conditions. Trans-membrane
applied potential V
±
2, 113
±
5, 243
±
9, and 386
±
10pA, respectively. Mean
±
S.D.,
n
≥
10
−
8
molar (M) in the aqueous phase bathing the lipid bilayer. The cis side was the electrical ground.
The aqueous phase contained 1.0 M NaCl, pH 7.0
=
150 mV. Alamethicin was added to the trans side of the lipid bilayer at
∼
n
r
tot
=
r
i
(5.24)
i
=
0
such that the changes of the properties of an alamethicin channel hosting a lipid
bilayer, such as thickness, lipid curvature, bilayer elasticity, etc. alter the value
of
r
tot
, but the value can be kept constant or at least comparable by changing
the alamethicin channel molar concentration in the aqueous phase. However, the
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