Biomedical Engineering Reference
In-Depth Information
300
200
100
0
−
100
120
100
80
60
40
20
0
20
40
60
80
100
120
−
−
−
−
−
−
Membrane voltage (mV)
(A)
200
= Measured photoemf
150
= True photoemf
100
50
0
−
50
−
120
−
100
−
80
−
60
−
40
−
20
0
20
40
60
80
100
120
(B)
Membrane voltage (mV)
5
=
G
p
+
G
m
=
G
m
=
G
p
4
3
2
1
0
−
120
−
100
−
80
−
60
−
40
−
20
0
20
40
60
80
100
120
(C)
Membrane voltage (mV)
FIGURE 15.13
DC photoelectric response of a bR-containing BLM. The pH was 6.9, and the temperature was 24ºC. (A) The pho-
tocurrent (
I
p
) is plotted as a function of membrane voltage. (B) The photoemf (
E
p
) is plotted as a function of mem-
brane voltage. The apparent photoemf is shown as open inverted triangles whereas the true photoemf, derived
according to Eq. (15.11), is shown as filled inverted triangles. (C) The apparent photoconductance (
G
p
G
m
) (open
squares, calculated by means of Eq. (15.10)), the measured dark conductance (
G
m
) (open triangles), and the true
photoconductance (
G
p
) (filled circles, obtained by subtracting
G
m
from the apparent photoconductance) are plot-
ted as functions of membrane voltage. The conductance data are connected with line segments for the sake of
easy data reading. Each set of data is also fitted with a straight line by the least square method. All the data were
taken from the same membrane. (From Fuller, B. E., Okajima, T. L., Hong, F. T. (1995). Analysis of the d.c. pho-
toelectric signal from model bacteriorhodopsin membranes: d.c. photoconductivity determination by means of
the null current method and the effect of proton ionophores.
Bioelectrochem. Bioenerg.
37:109-124.)
