Transport of α-Helical Peptides through α-Hemolysin and Aerolysin Pores

Publisher Website
Google Scholar
Abstract
A series of negatively charged α-helical peptides of the general formula fluorenylmethoxycarbonyl (Fmoc)-DxAyKz were synthesized, where x and z were 1, 2, or 3 and y was 10, 14, 18, or 22. The translocation of the peptides through single pores, which were self-assembled into lipid membranes, was analyzed by measuring the current blockade iblock and the duration tblock. The pores were either α-hemolysin, which has a wide vestibule leading into the pore, or aerolysin, which has no vestibule but has a longer pore of a similar diameter. Many thousands of events were measured for each peptide with each pore, and they could be assigned to two types: bumping events (type I) have a small iblock and long tblock, and translocation events (type II) have a larger iblock and shorter tblock. For type-II events, both iblock and tblock increase with the length of the peptides on both pores tested. The dipole moment and the net charge of each peptide has a major effect on the transport characteristics. The ratio of type-II/type-I events increases as the dipole moment increases, and uncharged peptides gave mostly type-I events. The structural differences between the two nanopores were reflected in the characteristic values of iblock, and in particular, the vestibule of α-hemolysin helps to orient the peptides for translocation. Overall, the results demonstrate that the nanopore technology can provide useful structural information but peptide sequencing will require further improvements in the design of the pores.

This publication has 0 references indexed in Scilit: