For SHELX there are two ways to fix selected atoms: either put AFIX 1 in front of the fixed atoms and AFIX 0 after them, or use the BLOC instruction. e.g.
BLOC 1 N_1 > C_53 N_57 > C61 N_62 CA_62 C_62 O_62 N_63 > LAST BLOC -1 N_1 > C_53 N_57 > C61 N_62 CA_62 C_62 O_62 N_63 > LAST would fix residues 54-56 and the side-chain of residue 62 (but you may need to consider the order of atoms). This would be easier than using AFIX if you are already using AFIX for riding hydrogens, however it is OK to fix atoms with AFIX 1 and then use HFIX in the same job to add hydrogens. I have deliberately chosen a complicated example to show how easy it is! More details on SHELXL refinements are now available from the CCP4 Wiki: http://strucbio.biologie.uni-konstanz.de/ccp4wiki/index.php/SHELXL and for SHELXC, D and E see: http://strucbio.biologie.uni-konstanz.de/ccp4wiki/index.php/SHELX_C/D/E Note that since this is a Wiki, users are encouraged to contribute! George Prof. George M. Sheldrick FRS Dept. Structural Chemistry, University of Goettingen, Tammannstr. 4, D37077 Goettingen, Germany Tel. +49-551-39-3021 or -3068 Fax. +49-551-39-2582 On Thu, 3 Apr 2008, U Sam wrote: > How one can fix position of few residues when refining in SHELX or Refmac5. > Thanks. Sam. > _________________________________________________________________ > Use video conversation to talk face-to-face with Windows Live Messenger. > http://www.windowslive.com/messenger/connect_your_way.html?ocid=TXT_TAGLM_WL_Refresh_messenger_video_042008
