Fluctuation patterns of voltage-induced ionic currents in black lipid membranes. Effect of α-Hemolysin.

COLMANO, G.N.; VAZQUEZ, R.F.; MOTTOLA, M.; CORVALÁN, N.A.; CLOP, P.D.; BAKAS, L.R.; PERILLO, M.A.

Sierra de la Ventana

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Biofísica; 2014

Sociedad Argentina de Biofísica

Previously1 we reported that the rise in holding potential (∆V) and cholesterol (CHO) content in planar lipid bilayers (BLM), increased the number of conductance states, the magnitude of conductance levels and favored the development of long-range autocorrelated (fractal) processes. This was explained as a CHO induced modulation of the ∆V threshold that allowed a percolation ofchannel behavior, where isolated channels become an interconnected network. Moreover, α-Hemolysin (HlyA) is a protein with a known capability of forming lytic pores in biomembranes2. Thus, in the present work we investigated the fluctuation patterns of ion currents through DOPC/CHO (0-30 mole%) BLMs, usingsymmetric bathing solution (10 mM HEPES-KOH pH 7,4, 150 mM NaCl, +/- 10 mM CaCl2) with or without 0-20 nM HlyA. Electrical current intensities (I) were measured in voltage clamped conditions between 0 and ± 200mV. The autocorrelation parameter α, derived from detrended fluctuation analysis (DFA) on I temporal fluctuation, showed that in BLMDOPC HlyA induced a transition from noncorrelated (α=0.5, white noise) to a long range correlated (0.5