With the Thermo Scientific Tundra Cryo-TEM, configured with the Thermo Scientific Falcon C Direct Electron Detector, you can visually resolve protein structures and produce 3D reconstructions down to 2.1 Å. The Tundra Cryo TEM can also be utilized for negative-stain electron microscopy, an easy and cost-effective method for the quality assessment of purified biological specimens at room temperature. In addition, the Tundra Cryo-TEM can visualize sections of resin-embedded cells and tissues or isolated particles of protein complexes and viral assemblies.
Single particle cryo-EM analysis
The Tundra Cryo-TEM can efficiently validate ligand and protein binding when in fast mode, taking over 10,000 images in as little as a few days’ acquisition time. With the Tundra Cryo-TEM, you can take a closer look at receptors that affect the central nervous system or investigate prokaryotic ribosomes. From Nobel –prize-winning discoveries, like TRPV5, to small potential drug targets, like GABAA receptors, the Tundra Cryo-TEM can help expand your scientific discovery by visually resolving structures and producing 3D reconstructions at ~2–5 Å resolution. When the Tundra Cryo-TEM is configured with a Falcon C Direct Electron Detector, the resolution can be improved, particularly for small and asymmetric protein complexes such as hemoglobin (64kDa).
Structure of hemoglobin (64 kDa), highlighting the heme binding pocket visualized with the Tundra Cryo-TEM.
Molecular structures determined using the Tundra Cryo-TEM
Drug discovery with the Tundra Cryo-TEM
Cryo-electron microscopy (cryo-EM) is rapidly drawing interest in structure-based drug discovery and design, since it can accurately and rapidly visualize to high resolutions the interactions between drug and receptor of a multitude of samples. Here we show two examples, a prototypical human membrane protein, the β3 GABAA receptor homopentamer, and a human CDK-activating kinase (CAK), both challenging proteins for traditional structural biology methods. Structures determined on the Tundra Cryo-TEM provide insight into inhibitor interactions and the basis for rational design of next-generation therapeutics.
Cryo-TEM sample optimization and connectivity
The Tundra Cryo-TEM can be used to optimize samples, offering efficient sample iteration and optimization. It serves as a valuable screening tool, providing biochemical sample optimization in less time than higher-level cryo-EM instruments.
Human GABAA (gamma-aminobutyric acid type A) receptor is a 200 kDa membrane protein and ligand-gated chloride ion channel that mediates inhibitory neurotransmission. Neuronal disorders such as epilepsy, insomnia, anxiety, and sleep disorders are a direct result of GABAA receptor neurotransmitters not functioning properly as chemical messengers in our brains. As an important therapeutic target, it is vital to understand the molecular mechanism by which these receptors mediate neurotransmission. However, even with decades of effort, only non-physiological forms of GABAA receptors have been crystallized and structurally resolved, even though physiological forms are needed to explain the receptors’ mechanism of action. The Tundra Cryo-TEM was used to optimize the sample, generating an initial structure of the stable conformation of the GABAA receptor with details that can identify ligand and nanobody binding. The map shows an atomic model fit with all the major side chains visible and a histamine (yellow) ligand in its binding pocket. The protein–protein interaction of mega-bodies (red/orange densities) with their receptors is also visible.
Rapid in-house sample-optimization of cryo-EM workflow shows how the Tundra Cryo-TEM is used to determine the right criteria for sample preparation to generate a high-resolution structure.
Room temperature TEM applications
The Tundra Cryo-TEM can be utilized for negative-stain electron microscopy, an easy and cost-effective method for the quality assessment of purified biological specimens at room temperature to quickly assess the stability, homogeneity, and concentration of purified samples. In addition, room temperature sections of resin-embedded cells and tissues or isolated particles of protein complexes and viral assemblies can also be visualized with the Tundra Cryo-TEM.
T20S proteasome stained with uranyl formate (2%) and visualized with the Tundra Cryo-TEM.
Sample courtesy of New York Structural Biology Institute.
Resin-embedded tobacco leaf visualized with the Tundra Cryo-TEM.
Sample courtesy of Sarah Powers, Doug Allen Lab, Janithri Wickramanayake, and Kirk Czymmek, Advanced BioImaging Laboratory, Donald Danforth Plant Science Center.
For Research Use Only. Not for use in diagnostic procedures.