Left-handed helices

Cryo-EM Data Processing
1

Hi,

I’m experiencing a problem that there are left-handed helices in the volume map after homogeneous or NU refinement. This problem seems to occur randomly among different micrograph datasets, as helix handedness in another project is OK (same protein samples and data aquisition parameters, collected separately on an Titan Krios).

Thank you.

Yiwei

2

Hi Yiwei,

Was your input model the correct hand? If performing ab initio reconstruction, you have equal chance to get a model with the correct or inverted hand. You can just invert the map (e.g. flip in z) if the hand is incorrect - it won’t affect anything else about the refinement.

Cheers
Oli

1 Like
3

Hi Oli,

That works, thank you.

Sincerely,
Yiwei