Biological nanopores having tunable pore diameters and uses thereof as analytical tools

The invention relates to the field of nanopores, in particular to engineered Fragaceatoxin C (FraC) nanopores and their application in analyzing biopolymers and other (biological) compounds, such as single-molecule (protein) sequencing. Provided is a system comprising oligomeric FraC nanopores comprised in a lipid bilayer, wherein the sum of the nanopore fraction in the heptameric (Type II) state and the nanopore fraction in the hexameric (Type III) state represents at least 60% of the total number of FraC nanopores