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One-of-a-kind electron microscope available for users of UCLA facility

BioPACIFIC MIP and California NanoSystems Institute offer powerful tool for determining three-dimensional molecular structure

While X-ray crystallography has long been the go-to method for biologists and chemists aiming to reveal the three-dimensional structure of proteins and small molecules, some cases defy characterization. If a protein does not form large enough crystals or a molecule is too small for direct imaging, the task may be better-suited for electron diffracation tomography, a technique commonly known as microcrystal electron diffraction (microED).

A new state-of-the-art tool for microED method is now available at the BioPolymers, Automated Cellular Infrastructure, Flow, and Integrated Chemistry Materials Innovation Platform (BioPACIFIC MIP) at UCLA, a National Science Foundation–funded user facility supporting research into sustainable, biologically derived molecules, polymers and materials.

The ThermoFisher Spectra 300-C is a unique transmission electron microscope (TEM) configured to optimize high-throughput performance for microED at multiple electron beam energies.

“Its versatility and precision engineering will uniquely enable breakthrough experiments in important areas of chemistry and materials research, including biomaterials”, says Jose Rodriguez, a UCLA professor in the Department of Chemistry and Biochemistry.

Electron diffraction tomography determines structure by acquiring multiple diffraction patterns at different angles and processing those patterns with software tools originally designed for X-ray crystallography. The technique is fast, allowing useful data to be acquired in minutes and processed within hours, as compared to days via cryogenic TEM or longer when using an X-ray synchrotron. By shortening the time to determine atomic-scale structure, this new tool tightens the feedback loop for informed discovery of new materials.

The ThermoFisher Spectra 300-C is a unique transmission electron microscope (TEM) configured to optimize high-throughput performance for microED at multiple electron beam energies. (Image credit: Marc Roseboro/CNSI)

The Spectra 300-C is the first Spectra-class microscope to offer a number of new enabling features for accelerated structure determination of small molecules, peptides/peptoids, and semi-crystalline polymers. Its large-gap electromagnetic pole piece provides room to maneuver while imaging, enabling a wider range of angles to be sampled to produce better structural determinations.

An integrated anti-ice device inhibits significant ice build up from water vapor in the vacuum, preventing ice contamination that can inhibit structure determination.

The instrument also comes equipped with a next-generation high-brightness field emission electron source. This cold field emission gun (X-CFEG) produces a beam of electrons that is more wave-like than beams generated by any other type of electron source. The more wave-like, the better electrons interfere after scattering from a sample.

Located in the California NanoSystems Institute at UCLA, the instrument is available to researchers from academia, non-profits, government organizations and industry via the BioPACIFIC MIP user program.

Prospective users can request general information about the Spectra 300-C, consultation about the microED technique or training and other access to the BioPACIFIC MIP facilities at biopacificmip@cnsi.ucla.edu.