ISSN:
1432-1424
Keywords:
hemocyanin channel
;
planar bilayer membrane
;
multistate transitions
;
channel kinetics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary The kinetics of the hemocyanin channel conductance transitions in black lipid membranes have been studied in two different ways. In one method, voltagejump current-relaxation experiments were performed with membranes containing many channels (102÷104). The steady-state conductance-voltage curves obtained are S-shaped and the slow kinetic processes (1–100 sec) for the approach to steady-state can be fitted by three exponentials. The three time constants were found to depend on the actual applied voltages, but not on the past history (preconditioning voltages). In the other method, membranes with one single channel were used and the spontaneous discrete fluctuations of conductance at constant voltage were analyzed. Slow fluctuations occur between four conductance levels with the lower ones preferred at high positive voltages. The voltage dependence of the conductance of each level and of the transition rates has been measured. A tentative model for the gating mechanism is suggested, which associates each conductance level to a configurational state of the channel and considers the transitions between them as a Markow jump process.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01875458
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