What is cryo-electron microscopy?
Cryo-electron microscopy (cryoEM) is an imaging technique used to visualize proteins and other macromolecules in a near-native state. This technique involves freezing samples of biomolecules in solution and then viewing them with an electron microscope.
In order to obtain high-resolution images, the sample must be vitrified, or frozen without ice crystals forming. The sample is then placed on a grid and bombarded with electrons. The electrons interact with the atoms in the sample, causing them to emit light. This light is captured by a camera and converted into an image.
Because cryoEM does not require that the biomolecule be purified or crystallized, it can be used to study a wide range of molecules, including those that are difficult to purify or crystallize. In addition, because cryoEM can be used to study biomolecules in their native environment, it can provide insights into how these molecules function in vivo.
The resolution of images obtained using cryoEM depends on several factors, including the type of microscope used, the size of the molecule being imaged, and the level of contamination present in the sample. Resolution can range from 3 Angstroms (Å) for large molecules imaged with a transmission electron microscope (TEM) to 0.5 Å for small molecules imaged with a scanning electron microscope (SEM). For comparison, one nanometer (nm) equals 10 Angstroms.
Cryoem has played vital role structural biology providing molecular architecture of various cell’s organelles like ribosome & mitochondria as well as viruses & bacteria at atomic details which were impossible earlier by any other techniques.”