Long lifetime alpha-hemolysin nanopores

An isolated polypeptide comprising an amino acid sequence selected from the group consisting of:

• (a) an amino acid sequence having at least 85% sequence identity to SEQ ID NO:
• 17, with the proviso that said amino acid sequence comprises:
• (a1) asparagine at a position corresponding to position 111 of SEQ ID NO:
• 17,
• (a2) glycine at positions corresponding to each of positions 126-131 of SEQ ID NO:
• 17,
• (a3) alanine at a position corresponding to position 144 of SEQ ID NO:
• 17, and
• (a4) asparagine at a position corresponding to position 147 of SEQ ID NO:
• 17;
• (b) an amino acid sequence having at least 85% sequence identity to SEQ ID NO:
• 18, with the proviso that said amino acid sequence comprises:
• (b1) glycine at a position corresponding to position 35 of SEQ ID NO:
• 18,
• (b2) asparagine at a position corresponding to position 111 of SEQ ID NO:
• 18,
• (b3) alanine at a position corresponding to position 144 of SEQ ID NO:
• 18, and
• (b4) asparagine at a position corresponding to position 147 of SEQ ID NO:
• 18;
• (c) an amino acid sequence having at least 85% sequence identity to SEQ ID NO:
• 19, with the proviso that said amino acid sequence comprises:
• (c1) glycine at a position corresponding to position 35 of SEQ ID NO:
• 19,
• (c2) asparagine at a position corresponding to position 111 of SEQ ID NO:
• 19,
• (c3) alanine at a position corresponding to position 113 of SEQ ID NO:
• 19,
• (c4) glycine at positions corresponding to each of positions 126-131 of SEQ ID NO:
• 19,
• (c5) alanine at a position corresponding to position 144 of SEQ ID NO:
• 19, and
• (c6) asparagine at a position corresponding to position 147 of SEQ ID NO:
• 19;
• and
• (d) an amino acid sequence having at least 85% sequence identity to SEQ ID NO:
• 20, with the proviso that said amino acid sequence comprises:
• (d1) an asparagine at a position corresponding to position 111 of SEQ ID NO:
• 20,
• (d2) an alanine at a position corresponding to position 113 of SEQ ID NO:
• 20,
• (d3) a glycine at positions corresponding to each of positions 126-131 of SEQ ID NO:
• 20, and
• (d4) an asparagine residue at a position corresponding to position 147 of SEQ ID NO:
• 20.