If you are using CCP4, it can accomodate P22121. However, just reindex in CCP4 to the correct setting with P21212.
Bernie Santarsiero On Thu, March 31, 2011 9:28 am, Anita Lewit-Bentley wrote: > Dear all, > > I would like to share my experiencde with a rather unexpected problem > of indexing conventions. Perhaps I can save people some time.... > > I have a crystal in the more unusual P21212 space-group (No 18). Its > unit cell lengths are b>a>c (please note). I systematically use XDS > for data integration, since so far it was able to handle even the most > horrible-looking spots. > > Now XDS indexed my data in space-group 18, but with the axes order > a<b<c! It had, in fact, "invented" a space-group P22121, which does > not exist. I did not realise this until I had spent a couple of weeks > with beautiful peaks in rotation functions, but hopeless results in > translation functions. It wasn't until I looked more closely into the > definition of the screw axes that I realised the problem. > > POINTLESS does not allow a reindexing of reflexions within the same > space-group, but fortunately REINDEX did the trick at the level of > intensities, because I like to use SCALA for careful scaling of my data. > > So, basically, beyond just warning people who might encounter similar > problems, I was wo,dering if XDS could perhaps reindex reflexions > according to Int. Table conventions once the screw axes of a crystal > system have been identified? > > With best wishes, > > Anita > > > Anita Lewit-Bentley > Unité d'Immunologie Structurale > CNRS URA 2185 > Département de Biologie Structurale & Chimie > Institut Pasteur > 25 rue du Dr. Roux > 75724 Paris cedex 15 > FRANCE > > Tel: 33- (0)1 45 68 88 95 > FAX: 33-(0)1 40 61 30 74 > email: ale...@pasteur.fr > >
