Proteins are structurally dynamic macromolecules that exist in various conformations of similar energies. The function of protein usually depends upon its structural formation which is often induced by ligand binding. These conformational changes are of great interest in proteomics
and biochemistry. In this work, we extended our knowledge to effectively detect structural perturbations of Mb (Myoglobin) in the presence of OA (Oleic acid) by using a ∼20 nm (diameter) silicon-nitride (Si3N4) nanopore. This interaction can be either specific or
non-specific depending upon the concentration of OA in Mb solution. Results of nanopore relied on the succession of current blockages as characterized by their duration, amplitude and event's number. In order to detect the interaction, three kinds of experiments were performed under three
different OA/Mb ratios and various event readouts were obtained. First of all, we took the volume ratio of OA/Mb as 4:1 and found that values of dwell time (td
) and current blockage (ΔIb
) were similar to Mb (only) translocation. Secondly, giving an
increment in the volume ratio of OA/Mb to 10:1 resulted in a significant increase in dwell time (td
) and current blockage (ΔIb
) level. Furthermore, a dramatic decrease in amplitude of ionic current blockage (ΔIb
) and dwell time
(td
) was observed at the ratio 20:1 of OA/Mb which indicated that OA/Mb interaction can cause structural instability of myoglobin. This may also disturb charge distributions on amino acid residues which results in variation of above-mentioned parameters. This approach of
nanopore sensing can be extensively employed in screening FABPs (Fatty acid binding proteins) and protein conformational studies.
Current Blockage of PSA molecular in Si3N4/Si/Si3N4 Sandwich Nanopore
