Protein tracking and detection of protein motion using atomic force microscopy

Area of Science:

• Biophysics
• Atomic Force Microscopy
• Protein Dynamics

Background:

• Proteins exhibit complex behaviors influenced by their environment.
• Atomic Force Microscopy (AFM) is a powerful tool for nanoscale imaging and measurement.
• Understanding protein dynamics is crucial for elucidating biological functions.

Purpose of the Study:

• To measure and characterize height fluctuations of single protein molecules using AFM.
• To differentiate intrinsic protein motion from instrumental noise or substrate interactions.
• To investigate potential correlations between protein type and observed dynamic behavior.

Main Methods:

• Utilized atomic force microscope (AFM) in fluid tapping mode.
• Employed a protein-tracking system for precise AFM tip repositioning over single protein molecules.
• Acquired height (z-piezo signal) data over proteins and support substrates in short time slices.

Main Results:

• Consistently observed higher height fluctuations when the AFM tip was over proteins compared to the support.
• Measurements over amphiphile patches showed noise levels similar to the support, suggesting protein-specific effects.
• Preliminary data indicated greater fluctuations for immunoglobulin G (IgG) and urease than for microtubules.

Conclusions:

• Protein height fluctuations are an intrinsic property, not solely due to tip-sample interactions.
• AFM can detect dynamic behaviors of proteins in their native-like fluid environment.
• Further studies are needed to correlate observed motions with specific protein structures and functions.