When cryoSPARC fails

We have a helical sample where both cryoSPARC and Relion fail completely. We suspect that it is due to the extremely small asymmetric unit, the tiny rise per subunit (0.1 Å), and the fact that almost all information is present at only better than ~ 4.5 Å (similar in this way to amyloid). Would there be anyone on the cryoSPARC team interested in looking at this?
Ed Egelman

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Hi @egelman,

Thank you for putting this on our radar. We have seen that there are a number of amyloid and amyloid-like datasets that Helical refinement struggles with, and we have similar suspicions that the core challenge is lack of information at low & mid resolutions (which are typically crucial for alignment). At this moment in time we are near our capacity for taking on additional projects, but we are aware this subclass of targets exists and it is in our longer-term vision to re-visit our alignment algorithms to better handle these kinds of targets.