Capture of a single molecule in a nanocavity

Area of Science:

• Biophysical chemistry
• Nanotechnology
• Protein engineering

Background:

• Transmembrane beta-barrel proteins form pores with potential for molecular manipulation.
• Cyclodextrins are known for their ability to encapsulate molecules.
• Controlling molecular transport at the nanoscale is crucial for advanced applications.

Purpose of the Study:

• To engineer a heptameric protein pore capable of simultaneously housing two cyclodextrin adapters.
• To create a defined nanochemical cavity within the protein pore.
• To investigate the behavior of charged organic molecules within this engineered nanostructure.

Main Methods:

• Protein engineering of a heptameric transmembrane beta-barrel.
• Incorporation of two distinct cyclodextrin adapters within the protein pore lumen.
• Single-channel electrophysiology recordings to analyze molecular interactions.
• Application of electrical potential to induce molecular capture and transport.

Main Results:

• Successful engineering of a protein pore accommodating two cyclodextrin adapters, forming a cavity of ~4400 cubic angstroms.
• Demonstration that charged organic molecules can be drawn into the cavity by an electrical potential.
• Observation of charged organic molecules shuttling between adapters for hundreds of milliseconds once trapped.

Conclusions:

• The engineered self-assembling nanostructure provides a controllable cavity for molecular interactions.
• This system shows promise for the development of multianalyte sensors.
• The nanostructure may offer novel strategies for controlling chemical reactions at the molecular level.