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Author Topic: Calculate torsion angles of the DNA, without taking into account the bases  (Read 7681 times)

Offline Andrea R

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Dear Dr. Xiang-Jun Lu,

I used versions of 3DNA earlier than the 2018 versions some time ago, in those versions it was possible to calculate the torsion angles of the sugar-phosphate backbone of DNA, without taking into account the bases, with the following command:

analyze -t = name.tor name.pdb

However in the new versions, this task is not possible anymore, it is necessary to have the nitrogenous bases or at least   N1, C2 or N9, C4 atoms. 

I was wondering if there is a new instruction or way to do that, because it would shorten my work route considerably. One of my study purposes is the optimized fragments of the Sugar-Phosphate Backbone, in these fragments the nitrogenous bases of the DNA are eliminated and replaced by a hydrogen (position N1 or N9) as shown in file attached .

Thank you very much,

Andrea R.

Offline xiangjun

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Re: Calculate torsion angles of the DNA, without taking into account the bases
« Reply #1 on: September 10, 2022, 09:38:10 pm »
Hi Andrea,

DSSR Pro can do what you want very easily, especially in combination with the --json option. See No more grant funding for 3DNA/DSSR.

Base atoms have always been necessary for the identification of nucleotides in order to calculate base-pair and backbone parameters in 3DNA v2.x, including the command you mentioned: analyze -t=torsions.out. However, since 3DNA v2.x is open source for academic uses, you can modify it to meet your needs.

Best regards,



Created and maintained by Dr. Xiang-Jun Lu [律祥俊] (
The Bussemaker Laboratory at the Department of Biological Sciences, Columbia University.