Cryo-Electron Microscopy (Cryo-EM) Services

Electron Microscopy (EM) has become an extremely popular method for the ultrastructural study of macromolecules, cells, and tissues. An aqueous biological sample is frozen rapidly and irradiated with a beam of electrons. A detector senses how the electrons are scattered, and a computer reconstructs the 3D-shape of the molecule.

Why do you need this service?

  • You have small amount of materials.
  • The material is hard to crystallize.
  • You are looking into the molecules in atomic details.
  • It is a large biomolecular complex (>150 kDa, up to 2000 Å).
  • You want to observe the real "native state" structure.

The Workflow of Our Cryo-EM Services (Take protein as an example)

Cryo-EM Services

Cryo-EM ServicesSample preparation
After protein purification, these samples will be treated with cryo-fixation. In this method, protein samples are placed on a specially treated EM grid consisting of tiny holes in a film supported by a metal frame. The grid is then plunged into liquid ethane to flash-freeze it, resulting in the protein samples being embedded in a thin layer of vitreous ice. Once the frozen-hydrated grid is prepared, it is placed in the electron microscope and kept at approximately -180 K throughout the experiment.
Cryo-EM ServicesEM imaging and data processing
  • Data collection
  • Initial 3D model calculation
  • Beam-induced motion correction
  • Micrograph screening
  • Automatic particle picking and normalization
  • 2D, 3D classification and refinement
Cryo-EM ServicesModel building and refinement
Using our high-performance computers and software packages, we can interpret EM maps and reconstruct them into 3D structural models that satisfy the principles of physics and stereochemistry. (Our scientists are also very experienced with challenging targets such as membrane proteins by manual intervention to improve the initial fit or even build de novo models.) After an initial model is built, refinement is performed to maximize the agreement between the model and experimentally observed data by adjusting atomic coordinates, B factors, and other parameters.

Featured Cryo-EM Services at Creative Biostructure

Your Specific Sample Types Observed by Cryo-EM

Creative Biostructure has extensive experience in using cryo-EM technology to study dynamic conformational changes and function of macromolecular complexes and has successfully applied this technology to characterize the structures of gene therapy and drug delivery particles. If you are interested in our cryo-EM services, please feel free to contact us to discuss your project.

References

  1. Grassucci R A, et al. Preparation of macromolecular complexes for cryo-electron microscopy. Nature Protocols. 2007, 2(12): 3239.
  2. Doerr A. Single-particle cryo-electron microscopy. Nature Methods. 2016, 13(1): 23-23.
  3. Thompson R F, et al. An introduction to sample preparation and imaging by cryo-electron microscopy for structural biology. Methods. 2016, 100: 3-15.
  4. Mahamid J, et al. Visualizing the molecular sociology at the HeLa cell nuclear periphery. Science. 2016, 351(6276): 969-972.
For Research Use Only. Not for use in diagnostic or therapeutic procedures.

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