|This page brings you to a channel recording
(QuickTime format) of a phospholipid bilayer containg Gramicidin D. The
fiugre below shows a snapshot of a computer screen to analyze the recording.
There are clearly six different levels (on horizontal) visible, the lowest
representing all channels closed, and each additional level the opening
of a channel unit (= peptide dimer). Note that except for three periods
of less than a second when all channels are closed, the membrane contains
up to five active channel units that constantly open (up) and close (down).
Also most channels have the same amplitude, one channel is clearly smaller,
i.e., carries less current or transports fewer ions per unit time (upper
left corner). This may be due to impurities in Gramicidin D preparation
(Gramcidin peptide is a mixture of peptides A or D).
The length of the trace shown here is 10.027 seconds and the amplitude
of the whole window (vertical) is 13.65 pA). Thus a single channel measures