  Noise profile of Voltage Dependent Anion Channel (VDAC) is investigated in
open channel state. Single-channel currents through VDAC from mitochondria of
rat brain reconstituted into a planar lipid bilayer are recorded under
different voltage clamped conditions across the membrane. Power spectrum
analysis of current indicates powerlaw noise of 1/f nature. Moreover, this 1/f
nature of the open channel noise is seen throughout the range of applied
membrane potential -30 to +30 mV. It is being proposed that 1/f noise in open
ion channel arises out of obstruction in the passage of ions across the
membrane. The process is recognised as a phenomenon of
self-organized-criticality (SOC) like sandpile avalanche and other physical
systems. Based on SOC it has been theoretically established that the system of
ion channel follows powerlaw noise as observed in our experiments. We also show
that the first-time return probability of current fluctuations obeys a powerlaw
distribution.
