Calling the Amino Acid Sequence of a Protein/Peptide from the Nanospectrum Produced by a Sub-nanometer Diameter Pore

The blockade current that develops when a protein translocates across a thin membrane through a sub-nanometer diameter pore (i.e., a nanospectrum) informs with extreme sensitivity on the sequence of amino acids that constitute the protein. Whereas mass spectrometry (MS) is still the dominant technology for protein identification, it suffers limitations. In proteome-wide studies, MS fails to sequence proteins de novo , but merely classifies a protein and it is not very sensitive requiring about a femtomole to do that. Compared with MS, a sub-nanometer diameter pore (i.e. a sub-nanopore) directly reads the amino acids constituting a single protein molecule, but efficient computational tools are still required for processing and interpreting the blockade current. Here, we delineate computational methods for processing sub-nanopore nanospectra and predicting electrical blockade currents from protein sequences, which are essential for protein identification.