Protein denaturation at the air-water interface and how to prevent it.

D'Imprima, Edoardo; Floris, Davide; Joppe, Mirko; Sánchez, Ricardo; Grininger, Martin; Kühlbrandt, Werner · Elife · 2019

basic_science · Level V

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Abstract

Electron cryo-microscopy analyzes the structure of proteins and protein complexes in vitrified solution. Proteins tend to adsorb to the air-water interface in unsupported films of aqueous solution, which can result in partial or complete denaturation. We investigated the structure of yeast fatty acid synthase at the air-water interface by electron cryo-tomography and single-particle image processing. Around 90% of complexes adsorbed to the air-water interface are partly denatured. We show that the unfolded regions face the air-water interface. Denaturation by contact with air may happen at any stage of specimen preparation. Denaturation at the air-water interface is completely avoided when the complex is plunge-frozen on a substrate of hydrophilized graphene.

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