Imaging of individual concanavalin a proteins by atomic force microscopy

Area of Science:

• Biophysics
• Biochemistry
• Materials Science

Background:

• Understanding lectin structure, like concanavalin A (Con A), is key for immune recognition.
• Current research often overlooks individual protein structure, focusing on cellular effects.

Purpose of the Study:

• To visualize the monomolecular structure of individual Con A proteins using AFM.
• To investigate the influence of varying Ni²⁺ concentrations on Con A protein morphology and arrangement.

Main Methods:

• Tapping-mode atomic force microscopy (AFM) was employed to image individual Con A proteins on mica.
• Con A protein samples were exposed to varying Ni²⁺ concentrations (5 mM to 50 mM).

Main Results:

• AFM successfully visualized individual Con A proteins, overcoming limitations of cellular-level studies.
• Increasing Ni²⁺ concentration led to increased surface roughness and altered Con A protein arrangements.
• At 50 mM Ni²⁺, Con A proteins exhibited four orientations; at 5 mM Ni²⁺, primarily two orientations were observed.

Conclusions:

• AFM provides a novel method for visualizing single protein molecules and their substructures.
• Ni²⁺ concentration significantly impacts Con A protein surface interactions and orientations.
• This technique offers insights for protein-based assays and understanding protein-surface dynamics.