Abstract

Liquid-phase electron microscopy (LPEM) is capable of imaging native (unstained) protein structure in liquid, but the achievable spatial resolution is limited by radiation damage. This damaging effect is more pronounced when targeting small molecular features than for larger structures. The matter is even more complicated because the critical dose that a sample can endure before radiation damage not only varies between proteins but also critically depends on the experimental conditions. Here, we examined the effect of the electron beam on the observed protein structure for optimized conditions using a liquid sample enclosure assembled from graphene sheets. It has been shown that graphene can reduce the damaging effect of electrons on biological materials. We used radiation sensitive microtubule proteins and investigated the radiation damage on these structures as a function of the spatial frequencies of the observed features with transmission electron microscopy (TEM). Microtubule samples were also examined using cryo-electron microscopy (cryo-TEM) for comparison. We used an electron flux of 11 ± 1-16 ± 1 e-/Å2s and obtained a series of images from the same sample region. Our results show that graphene-encapsulated microtubules can maintain their structural features of spatial frequencies of up to 0.20 nm-1 (5 nm), reflecting protofilaments for electron densities of up to 7.2 ± 1.4 × 102 e-/Å2, an order of magnitude higher than measured for frozen microtubules in amorphous ice.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.