Hi Sabuj, You can make surfaces that surround a set of atoms without making a separate PDB file. For example, if you have those atoms selected already, just use the command: surfcat mygroup sel where "mygroup" could be whatever you choose to name this set of atoms and "sel" means what is currently selected. Then, the command surface mygroup will show surface surrounding that group. There are several ways you could select the atoms of interest, and it sounds like you already figured out that part; the following detailed example is just one possibility: open pdb:2gbp sel :glc z<4.5 ~sel :glc ~sel solvent surfcat nearby sel ~sel surf nearby Here I opened a glucose-binding protein structure, selected all residues with any atom within 4.5 A of the ligand glucose (glc), then subtracted glucose itself and waters from the selection. Then I made the selected atoms a surface category with "surfcat," unselected them, and showed the corresponding surface. If you really want to save the selection to a file, it can be done on unix systems. Chimera can send information on what atoms are displayed to the system, and then the system command "cat" can send the information to a file. In Chimera, if the atoms of interest are selected: show sel pdbrun nouser cat > ~homedir/myfile.pdb (where "homedir" is your username) saves the displayed atoms to a PDB file named myfile.pdb in your home directory. It is necessary to use show (which undisplays everything else) since pdbrun includes all atoms that are displayed. The coordinates are transformed, so will be different from the original coordinates if you have moved the view around. If you want the untransformed coords, use the "reset" command before the "pdbrun" command. This process doesn't work on Windows as there is no cat command. I hope this helps, Elaine =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Elaine C. Meng, Ph.D. Computer Graphics Lab and Babbitt Lab meng@cgl.ucsf.edu http://www.cgl.ucsf.edu/home/meng/index.html =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=