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bioRxiv · 10.1101/087841

Cryo-EM structure of haemoglobin at 3.2 A determined with the Volta phase plate

Khoshouei, M.·Radjainia, M.·Baumeister, W.·Danev, R.
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Abstract

With the advent of direct electron detectors, the perspectives of cryo-electron microscopy (cryo-EM) have changed in a profound way1. These cameras are superior to previous detectors in coping with the intrinsically low contrast of radiation-sensitive organic materials embedded in amorphous ice, and so they have enabled the structure determination of several macromolecular assemblies to atomic or near-atomic resolution. According to one theoretical estimation, a few thousand images should suffice for calculating the structure of proteins as small as 17 kDa at 3 [A] resolution2. In practice, however, we are still far away from this theoretical ideal. Thus far, protein complexes that have been successfully reconstructed to high-resolution by single particle analysis (SPA) have molecular weights of ~100 kDa or larger3. Here, we report the use of Volta phase plate in determining the structure of human haemoglobin (64 kDa) at 3.2 [A]. Our results demonstrate that this method can be applied to complexes that are significantly smaller than those previously studied by conventional defocus-based approaches. Cryo-EM is now close to becoming a fast and cost-effective alternative to crystallography for high-resolution protein structure determination.

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Khoshouei, M., Radjainia, M., Baumeister, W., Danev, R.. 2016-11-15. Cryo-EM structure of haemoglobin at 3.2 A determined with the Volta phase plate. https://doi.org/10.1101/087841

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