I'd try first Mosflm, a cup of tea and two images. I'll get to the cup in a minute.
Read two images or three which are 90 degrees apart (three incase you have a cubic space group). Then take a sip and start manually removing spots which you believe belong to the other lattice, then index and see if you get a decent cell which overlaps with most of the reflections. It might help to look at a movie of your dataset, so that you can distinguish which lattice points belong to which crystal. As an alternative approach I believe Mosflm can use JPG images, so convert your dataset to JPG and remove those spots which belong to the other lattice in Photoshop. This approach might lead you to a "dataset" and provide you with a cell, but I think there are better ways of spending time. Now XDS, you write it failed, why ? Are you indexing over the whole dataset ? Do you have the beam position right ? I'd try to give it the P1 cell it suggests and then process the whole dataset even if it will be incomplete. Then run pointless and see if you get another suggestion for a space group & cell. With that information I would then go back into IDXREF.LP and see if a similar cell was picked up by XDS and try it with that. You will have a lot of reflections which will be rejected (because they belong to the second lattice) but you should be able to extract sufficient information to be able to work with the data. Next, your crystals, have you tried seeding them to get them grown individually ? Decreased protein concentration, larger drop volume, different ratios, all other usual things that come to mind ? Good luck ! Jürgen - Jürgen Bosch Johns Hopkins Bloomberg School of Public Health Department of Biochemistry & Molecular Biology Johns Hopkins Malaria Research Institute 615 North Wolfe Street, W8708 Baltimore, MD 21205 Phone: +1-410-614-4742 Lab: +1-410-614-4894 Fax: +1-410-955-2926 http://web.mac.com/bosch_lab/<http://web.me.com/bosch_lab/> On Feb 11, 2011, at 11:06 AM, pravinkumar jagtap wrote: Hi to all, I have crystals which grow as joint crystals i.e two crystals are joined to one another. I tried to seperate the two and collect dataset but the resolution is not good( probably I am harming the crystals during seperation). Also I collected a dataset with the joined crystals in the loop and I got resolution up to 3.5 A on synchrotron. But when I am trying to index this dataset, the XDS is failing . I also tried to use mosflm but it is also giving warning message that the unit cell parameters are too inaccurate. And this all seems to be because of the two crystals in the loop. Can anyone suggest any strategy which I should take for indexing this dataset. Thanks, Pravin Kumar
