Bioorganic Models for Protein Ion Channels

摘要

For biophysical characterization of ion channels peptides. We are using single-channel voltage clamp methods to study the model ion channel peptide, Ac-(LSSLLSL)3-CONH2 in an attempt to determine how selective it is for the conductance of cations versus anions. Both ends of the peptide are masked with neutral blocking, groups, allowing us to eliminate effects that are due to formal charges. Because the peptides can reorient upon a voltage change, we must use voltage pulses or fast ramps (approximately 100 msec) to measure full current-voltage relations on single open channels; the longer lifetime of the acetylated peptide facilitates this measurement. The open channel I-V relation rectifies in symmetrical 1 M KC1, with larger currents at the holding potential than at the opposite potential. (According to our gating model, the larger currents flow from C-terminus to N-terminus).