PDFIn theory, this method is “perfect” for evaluating proteins, states Giovanni Maglia, a chemical biologist at the University of Groningen who recently published a proteasome-nanopore that can unfold proteins for sequencing. The helicase is already known to work for DNA sequencing, he keeps in mind, and it pulls the DNA through the pore in a controlled method. Maglia points out that the approach is limited to peptides that are 26 amino acids or shorter. This is since the helicase sits on top of the pore and can only pull the molecule by its DNA tail.Dekker acknowledges this limitation but keeps in mind that this read length is enough to discriminate all proteins in the human proteome if they are burglarized pieces. The nanopore-based technique requires smaller samples than does mass spectrometry– a commonly used protein analysis approach– and would be able to find rare variations, something mass specification cant, Dekker says.
After a zap of voltage sends out the conjugated particle through the nanopore, the Hel308 helicase walks on the DNA section, pulling both the DNA and the attached peptide back through the nanopore. As with DNA sequencing, ratcheting the peptide through the nanopore alters the ion present, and the scientists can link the changes to a specific series of amino acids in their created peptide. A helicase particle then strolls along the DNA hair, effectively pulling the DNA and attached peptide back through the pore. As the peptide passes through, changes in the present across the membrane can be determined, providing clues to the amino acid composition of that stretch of the peptide.