One other thing - PyMOL has a flag which determines whether the density values will be normalised - if this flag is not set, then
isomesh mesh_name, map_name, 1 will contour the map at 1-sigma; to contour at an absolute value, you must do set normalize_ccp4_maps=0 BEFORE loading the map. If the flag is set, the program will print some information about the calculated mean and std deviation when you load a map. Commonly-used settings like this can be put in your ~/.pymolrc file (at least on a UNIX system), so that they are executed whenever PyMOL starts up. Gareth ------------------------------------------------------------------------------- Gareth Stockwell EMBL - European Bioinformatics Institute Wellcome Trust Genome Campus Hinxton Cambridge CB10 1SD gar...@ebi.ac.uk Tel 01223 492548 http://www.ebi.ac.uk/~gareth