Fluctuation patterns of voltage-induced ioni c currents in black lipid membranes. Effect of alpha-Hemolysin.

NICOLÁS G. COLMANO; R. F. VAZQUEZ; MILAGROS MOTTOLA; NATALIA A. CORVALÁN; PEDRO D. CLOP; LAURA R. BAKAS; MARIA A. PERILLO

Bahía Blanca

Congreso; XLIIIReunión Anual SAB 2015; 2014

Sociedad Aregentina de Biof{isica

Previously we reported that the rise in holding potential (deltaV) 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 explainedas a CHO induced modulation of the deltaV threshold that allowed a percolation of channel behavior, where isolated channels become an interconnected network. Moreover, alpha-Hemolysin (HlyA) is a protein with a known capability of for minglytic pores in biomembranes. Thus, in the present work we investigated the fluctuation patterns ofion currents through DOPC/CHO (0-30 mole%) BLMs, using symmetric bathing solution (10 mM HEPES-KOH pH 7,4, 150 mM NaCl, +/- 10 mMCaCl2) with or without 0-20 nM HlyA. Electrical current intensities (I) were measured in voltage clamped conditions between 0 and +/- 200mV. The autocorrelation parameter alpha, derived from detrended fluctuation analysis (DFA) on I temporal fluctuation, showed that in BLM_DOPC. HlyA induced a transition from non-correlated (alpha = 0.5,white noise) to a long range correlated (0.5 < alpha < 1) behavior at deltaV >100 mV. In CHO containing BLMs, the effect ofthe steroidprevailed.