[Chimera-users] measurement of arc-length (geodesic distance) between atoms on a protein surface?

[Wiener, Michael C (mcw2s)]

New subscriber here, with a question about whether Chimera currently can measure arc-length (geodesic distance) between atoms on a protein surface (or, for example, generate a Calpha-Calpha distance matrix of this).

I am (very) interested in measuring/obtaining distances between pairs of Calpha carbons (or pairs of other atoms, I suppose) of different amino acids that are on the surface of a protein. While the difference between arc-length (geodesic) distance and cartesian/Euclidean distance will be negligible if, for example, the two solvent-exposed Calpha atoms are on the same solvent-exposed face of an alpha-helix, the difference could be significant for residues on opposite “sides” of the protein. I did see that there are ways in Chimera to get distances between an atom and a molecular surface, or to place markers on the surface & obtain the lengths between these for a distance, but I am VERY interested in whether one can simply select two atoms and get the arc-length (geodesic) distance or generate an arc-length (geodesic distance) matrix of all surface-exposed Calpha pairs.

Several computational methods have been developed for this sort of thing, via graph theoretical or other approximation method, and have been published (Hall et al., Biophysical Chemistry 190-191 [2014] 50-55). However, I have not yet (?) found this to be in any graphics/analysis program. I’m thinking that this could perhaps be useful to someone besides me?

Any assistance would be greatly appreciated. My lab and I are (much) more on the user side than the developer side, so are not currently well-positioned to code it in-lab.

Regards,

-MW

(btw, if anyone in the “Chimera Group” wants to know more about why I am interested in this, don’t hesitate to send me an email. This type of distance calculation is related to some experimental technology/assay development that we are doing.)

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Michael C. Wiener. Ph.D., Professor
Department of Molecular Physiology and
                Biological Physics
University of Virginia
Charlottesville, VA 22908-0886
434-243-2731 (office); 434-243-2730 (lab)


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