Single Protein Molecule Detection with a Transfer-APTamer (Piston) Sliding in a Protein Pore

Abstract

Aptamers are specific oligonucleotide molecules that bind to various biologically important target molecules. Nanopores are powerful tools for the identification and detection of single molecules, such as DNA, RNA and proteins. α-hemolysin nanopore is utilized to sense the single protein molecule with a transfer-aptamer (piston). The transfer-aptamer (piston) containing polyethylene glycol (PEG) has functions as identified which zone of the beta barrel of pore. Here we report the formation of reversible signature signals using protein engineering, and characterized change the pore conductance depend on special design of transfer-aptamer (piston). The transfer-aptamer was bound with thrombin, which can be trapped to the pore opening and distinguished signature current block compared the thrombin being released from the transfer-aptamer (piston). But, the signal of aptamer only contains DNA which is indistinguishable with or without thrombin. By containing specific tail of aptamer, presence of single protein molecule, we capture the reversible thrombin signature signal using protein pore. The transfer-aptamer (piston) can be used as detector of different ions for nanomachine, nanomaterials, and folding process.