Figure 2

Typical recordings of ion current through a single Maltoporin trimer in presence of modified maltohexaose (see [16] for details). (A) Shows the unmodified maltohexaose and on the right hand side the modified sugar molecule. We designed this molecule according the crystal structure to guarantee the low penetration ability from one side. (B) M6-ANDS was added to trans (left) and then to cis (right). Sugar analogue modulates ion current only to the cis-side, the side of Maltoporin addition. The average residence time is 5.0 ms. (C) First, M6-ANDS was injected to the trans-side and no variation in the ion current occurs. As control, maltohexaose was added to the same side (left). The natural substrate is translocated demonstrating that it enters the channel from trans with the reducing end first. Then, M6-ANDS was added additionally to the cis-side (right) generating long current interruptions superimposed to maltohexaose blockade events seen in the figure of the left side. The dashed lines corresponding to zero current. Membrane bathing solution was 1 M KCl, 10 mM Tris, 1 mM CaCl₂, pH 7.4, the applied voltage was + 150 mV.