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.; BAKÁS, L.S.; PERILLO, M.A.

Bahía Blanca

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

Sociedad Argentina de Biofísica

Previously1 we reported that the rise in holding potential (DV) 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 DV threshold that allowed a percolation of channel 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, using symmetric 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 a, derived from detrended fluctuation analysis (DFA) on I temporal fluctuation, showed that in BLMDOPC HlyA induced a transition from noncorrelated (a=0.5, white noise) to a long range correlated (0.5<a<1) behavior at DV>100 mV. In CHO containing BLMs, the effect of the steroid prevailed. Acknowledgements: Foncyt, Conicet, SeCyT-UNC. 1. Corvalán NA et al. BBA Biomembranes 2013, 1828, 1754. 2. Bakás et al. Biophys J. 2006, 91, 3748.