Re: [ccp4bb] alternating strong/weak intensities in reciprocal planes - P622

2007-08-31 Thread Eleanor Dodson
If you have a high off origin peak at 0 0 0.5 you must have absences along the 00l axis also consistent with P63 22. So you need to test both P6322 and P6 22 And is the tetramer generated by crystal symmetry or is the whole thing in the asymmetric unit? Eleanor Jorge Iulek wrote: Dear all,

[ccp4bb] alternating strong/weak intensities in reciprocal planes - P622 - feedback / quasi SUMMARY

2007-08-28 Thread iulek
I got several suggestions. I thought it is time to answer some questions, prepare a partial quasi- summary and give some more feedback. Please, keep sending me any more insights and suggestions you might have. Briefly, the problem is: P622 (no systematic abscences), strong spots at

[ccp4bb] alternating strong/weak intensities in reciprocal planes - P622

2007-08-27 Thread Jorge Iulek
Dear all, Please, maybe you could give some suggestions to the problem below. 1) Images show smeared spots, but xds did a good job integrating them. The cell is 229, 229, 72, trigonal, and we see alternating strong and weak rows of spots in the images (spots near each other, but rows more

Re: [ccp4bb] alternating strong/weak intensities in reciprocal planes - P622

2007-08-27 Thread Dale Tronrud
On possibility for #5, the B factors all dropping to the lower limit during refinement. If you are including all of your low resolution data (which you should) but have not used a model for the bulk solvent scattering of X-rays (which would be bad) then you will observe this result. The

Re: [ccp4bb] alternating strong/weak intensities in reciprocal planes - P622

2007-08-27 Thread Bart Hazes
Hi Jorge, The strong h, k, l=2n and weak h, k, l=2n+1 pattern suggest pseudo body centering. Does the off-origin Patterson peak lie at/near 0.5 0.5 0.5? You could get pseudo body centering if an NCS 2-fold lies parallel to a crystallographic 2(1) or 6(3) screw axis, with the NCS 2-fold a

Re: [ccp4bb] alternating strong/weak intensities in reciprocal planes - P622

2007-08-27 Thread Rizkallah, PJ (Pierre)
: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of Jorge Iulek Sent: 27 August 2007 12:48 To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] alternating strong/weak intensities in reciprocal planes - P622 Dear all, Please, maybe you could give some suggestions to the problem below. 1) Images