How to look at proteins without distorting them

THIS year’s Nobel prize for chemistry has been awarded to Jacques Dubochet of Lausanne University, in Switzerland, Joachim Frank of Columbia University, in New York, and Richard Henderson of the Laboratory for Molecular Biology, in Cambridge, Britain. Each has contributed to the development of cryoelectron microscopy, a technique that permits the shapes of biological molecules, such as proteins, to be seen without many of the difficulties involved in preparing them for older techniques, such as X-ray crystallography or conventional electron microscopy.

Dr Dubochet invented a way of freezing samples that has proved crucial to the technique. A sample—say, a protein of interest—is suspended in water and then dripped onto a thin metal mesh. This mesh is then plunged into liquid ethane, at a temperature of around -180°C. The speed of plunging is crucial. Do it too slowly and the water in the sample will turn into ice crystals that destroy the protein molecules. If done fast…Continue reading

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