Opening values and the definition for base-pair parameters

[azurelegend]

Hi,

I'm using X3DNA to analyze the base-pair parameters and the base step parameters recently. My structure is parallel-stranded DNA and all the base pairs are non-canonical pairs. I found that some parameters are very different from a standard DNA structure. For example, the opening will have values like 170, -170, 90. I read some of the related posts and papers but still confused about the definitions. So what do the 170s and 90s value mean? And what is the difference between 170 and -170? How does X3DNA calculate the opening, that is, which angle does it actually calculate?

And I also have a further question that how does X3DNA calculate other base-pair parameters? I think I'm getting confused even from the beginning, how were the (o1, x1, y1 ,z1) and (o2, x2, y2, z2) for each base in a certain base-pair defined?

Thanks in advance,
Jing

[xiangjun]

Hi Jing,

Thanks for using 3DNA, and for posting your questions on the Forum. Your confusions about the details are understandable, and can be clarified most effectively using concrete examples. Do you have examples with opening ~90 and 180?

Since 3DNA source code is available, you can dig into it to see exactly how the base reference frames are defined and how the various parameters are calculated.

Best regards,

Xiang-Jun