Figure 1.

Schematic overview of the chop-n-drop fingerprinting method

(A) A protein is unfolded by an unfoldase and fragmented by a proteasome directly introduced above a nanopore. The protease is engineered to lyse proteins at particular residues.

(B) As the fragments pass the pore, a change in electrical current through the pore is measured.

(C) The molecular weights of the fragments are estimated from the magnitudes of the current changes.

(D) Finally, the produced sequence of fragment weights is aligned to database fingerprints of known proteins to identify the protein.