Re: [ccp4bb] Twinning in C 2 2 21

Unit cell dimensions don’t really matter here. If it’s a centred lattice you won’t be able to index it correctly in a primitive system even though C222 and P222 both have a<>b<>c and alpha=beta=gamma=90. Ditlev --- Ditlev E. Brodersen Lektor, Associate Professor Department of Molecular

Re: [ccp4bb] structure with missing density

Dear Deepanshu, Is the primary sequence in the neighbourhood of your missing strands conserved? Perhaps that part differs in your structure relative to the search model. Have you tried omitting the region from MR and rerunning refinement without to see if some new density pops up? If not,

Re: [ccp4bb] How big are my solvent channels in my protein crystal?

I guess you could expand your structure using SYMEXP and measure across the solvent channels in PyMOL using the Measure tool? Nevertheless, I don't think this sort of exercise is very useful. Crystal soaking is a highly empirical procedure, which in most cases is based on pure trial-and-error.

Re: [ccp4bb] R-merge is too high !!

1) Double check space group (run POINTLESS with unmerged data). 2) Process only as much data as needed for full completenes and see what you get (Rpim is OK, so the means of your structure factors are good, which also is consistent with your low refinement R factors and the maps). Best, Ditlev