[Chimera-users] Question regarding Chimera Measurements

[Shahmoradian, Sarah H]

Hello,
This is an urgent question and your help would be appreciated. I am trying to find a way to perform measurements in my tomogram volume file (.rec file). I tried using the "Distances" option under Tools --> Structure analysis, but this requires two "atoms." My tomogram does not depict at the atomic resolution and I would like to measure the distance between one area on my tomogram density and another area on the tomogram density. These measurements would be through a 3D section. Could you please let me know how I could do this?
Furthermore, I have a question about the scale bar -- when the program generates a default scale bar, how does the program assign the default value to the scale bar size? Does it read the header info from my tomogram file? I am concerned because when I change the label name from Angstrom to nanometers, the scale bar size stays the same-- how then, would I be able to assign an accurate scale bar that would change accordingly with the alterations in scale (Angstrom to nm, etc)? Please let me know if I need to clarify further. Your assistance would be appreciated!


Sincerely,
Sarah Shahmoradian

Molecular Physiology and Biophysics (Baylor College of Medicine)
Pre-doctoral fellow, Nanobiology Interdisciplinary Graduate Training Program (Rice University)