Browsing by Author "WOLFF, D"
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- ItemLARGE CATION-SELECTIVE PORES FROM RAT-LIVER PEROXISOMAL MEMBRANES INCORPORATED TO PLANAR LIPID BILAYERS(1986) LABARCA, P; WOLFF, D; SOTO, U; NECOCHEA, C; LEIGHTON, FFusion of a highly purified fraction of rat liver peroxisomal membranes to planar lipid bilayers incorporates large, cation-selective voltage-dependent pores. The PK/PCl ratio of these pores estimated in KCl gradients, is close to 4. The pores display several conductance states and spend most of the time open at voltages near 0 mV, closing at more positive and negative voltages. At voltages near 0 mV the most frequent open state has a conductance of 2.4 nS in 0.3 M KCl. At voltages more positive and more negative than 10 mV the most frequent open state displays a conductance of 1.2 nS in 0.3 M KCl. With these results pore diameters of 3 and 1.5 nm, respectively, can be estimated. We suggest that these pores might account for the unusually high permeability of peroxisomes to low molecular weight solutes. Fusion also incorporates a perfectly anion-selective, two-open states channel with conductances of 50 and 100 pS in 0.1 m KCl.
- ItemTHE MAJOR THIOBACILLUS-FERROOXIDANS OUTER-MEMBRANE PROTEIN FORMS LOW CONDUCTANCE ION CHANNELS IN PLANAR LIPID BILAYERS(1992) SILVA, M; FERREIRA, A; RODRIGUEZ, M; WOLFF, DA protein isolated and purified from the outer membrane of the acidophilic, chemolithotrophic bacterium, Thiobacillus ferrooxidans with an oligomeric molecular weight of 90 000 Da (p90) was incorporated into phosphatidylethanolamine planar lipid bilayers. The protein formed slightly anionic channels in KCl solutions, with a conductance of 25 pS in 100 mM KCl. The current-voltage relationship was linear between +/-60 mV, and the conductance was a saturating function of the salt concentration. These channels fluctuated from a single open to closed state at low potentials, but present flickering activity at higher potentials.