From Tube to Structure: SPA Cryo-EM Workflow Using Apoferritin as an Example

Area of Science:

• Structural Biology
• Biophysics
• Biochemistry

Background:

• High-resolution structure determination is crucial for understanding biological processes.
• Cryogenic Electron Microscopy (cryo-EM) has emerged as a powerful technique for molecular imaging.
• Standardized protocols are essential for reproducible and reliable results in cryo-EM.

Purpose of the Study:

• To present a standard protocol for high-resolution structure determination using Single Particle Analysis cryo-Electron Microscopy (SPA-EM).
• To utilize apoferritin as a standard sample for demonstrating the protocol's efficacy.
• To provide a comprehensive guide for researchers new to SPA-EM.

Main Methods:

• Purified apoferritin applied to glow-discharged support.
• Flash-freezing of samples in liquid ethane.
• Data collection using electron microscopy with optimized alignments.
• Processing of collected movies for 3D reconstruction.

Main Results:

• Successful application of a standard protocol for SPA-EM.
• Generation of high-resolution 3D reconstruction of apoferritin.
• Demonstration of reproducible structure determination using a standard sample.

Conclusions:

• The presented protocol provides a reliable method for high-resolution structure determination via SPA-EM.
• Apoferritin serves as an effective standard sample for validating cryo-EM protocols.
• This protocol can facilitate advancements in structural biology research.