It's a very common problem to calculate the twist angle between to beta-strands or two alpha-helix. So I am wondering if Chimera can fit a group of atoms into a straight line, and give the angle of two fitted line. If chimera does do this, hopefully somebody can tell me how to do this. If not, it would be worthwhile to add this function in. Thank you very much! Happy holiday! Mingfeng
Hi Minfeng, Currently Chimera does not do these things, but this is a good suggestion, and we will put it on our requested features list. You can see the axes of strands and helices and measure the distances and angles between them using WebMol. I think the axes are not always one straight line - sometimes different straight segments are joined together to make a "bent" axis - but otherwise it sounds just like what you wanted. You can try WebMol at http://www.cmpharm.ucsf.edu/cgi-bin/webmol.pl Enter your PDB ID of interest, and after it shows up in WebMol, pick Msure ... Pack from the WebMol interface. The axes will be drawn on the structure, and the values of the measurements will be shown in a separate text window. Happy Holidays to you too! Elaine ----- Elaine C. Meng, Ph.D. meng@cgl.ucsf.edu UCSF Computer Graphics Lab and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco http://www.cgl.ucsf.edu/home/meng/index.html