Dear ccp4 users,
I have a reflections file obtained from a crystal initially scaled
in H3. All the attempts to phase by Molecular Replacement were not
successful and I succeeded only in P1. Based on previously solved
structures from the same protein, I suspected that twinning affected
crystals; so I used Twin refinement in Refmac. The program gave
indication of 3 domains:
Twin operator: H, K, L : Fraction = 0.335
Twin operator: H, L, -H-K-L: Fraction = 0.332
Twin operator: H, -H-K-L, K: Fraction = 0.333
With P1 and twin refinement I obtained a reasonable initial value of FOM
(0.50) but R/Rfree still remain at very large values (0.46/0.49).
I am not sure about twinning and data handling in presence of 3 twin
domains and I will appreciate a lot if someone will suggest me how to
deal out with these data.
Thanks
Fulvio
--
Fulvio Saccoccia, PhD
Sapienza University of Rome
Dept. of Biochemical Sciences "A. Rossi Fanelli"
Piazzale Aldo Moro, 5
00185 Rome (Italy)
