As only small part of the molecules is shown and it appears to be in poly-alanine representation, more interesting thing may happened apart of "numerical instabilities" of Fourier transform. These can be mutually exclusive conformations that brake local symmetry but preserve overall symmetry. The alts penetrate forbidden region of the symmetry, but only from one molecule. I have seen such things. BTW what program was used to calculate maps? FF Dr Felix Frolow Professor of Structural Biology and Biotechnology, Department of Molecular Microbiology and Biotechnology Tel Aviv University 69978, Israel
Acta Crystallographica F, co-editor e-mail: mbfro...@post.tau.ac.il Tel: ++972-3640-8723 Fax: ++972-3640-9407 Cellular: 0547 459 608 On Nov 5, 2012, at 12:22 , Tim Gruene wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Dear Shutong Xu, > > one often finds artefacts on special positions. As far as I > understand, these are numerical 'instabilities' or artefacts rather > than of chemical origin. > > Best, > Tim > > On 11/05/2012 10:50 AM, Crystal Xu wrote: >> Dear all, >> >> I am now determining a structure at 2.2 A resolution. The space >> group is C2, and there is only one molecular in an ASU. During the >> refinement, some weird electron density appears right on the >> two-fold axis. Does anyone have any idea what could this be? Thanks >> a lot. Best regards >> >> Shutong Xu >> > > - -- > - -- > Dr Tim Gruene > Institut fuer anorganische Chemie > Tammannstr. 4 > D-37077 Goettingen > > GPG Key ID = A46BEE1A > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.12 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ > > iD8DBQFQl5NkUxlJ7aRr7hoRAkUtAKC/6mrt5LdcG9bjZm3rN6UfDzpotQCg7B20 > WknHYPcUECMxk//k9zKjiqE= > =WCPn > -----END PGP SIGNATURE-----
