Dear All:
Hi. I have a question about selecting weighing term during restrained
refinement using Refmac5 of CCP4 packages.
For a 300kDa homodimer protein structure at 2.5A, 91% complete. I obtain
optimal R and Rfree by using NCS tight restraints of the peptides of the two
monomers. Weighing term 0.15 gives (R=0.22, Rfree=0.28) and weighing term 0.1
gives(R=0.23, Rfree=0.28). Higher weighing term gives larger difference between
R and Rfree.
Is there a criteria or special range of choosing weighing term? Is
weighing term 0.1 too small? I read the references by Ian Tickle (Acta Cryst D,
1998 and 2000)on R and Rfree ratio, those helped a lot but I still do not know
the key of weighing term.
Thanks so much.
Best,
Hongnan Cao
Biochemistry Department
UC Riverside
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