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Questions and answers > DNA/RNA-protein interactions (SNAP)

Difference between pi-stacking and pi-pair in SNAP

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akakios:
Dr. Xiang-Jun Lu,

Thank you for the amazing software. I am using it for my research.
I tried to find the definition of pi-stack and pi-pair in the output of SNAP but
could not find it.

Could you tell me the difference or the docs describing about it, please?

Takayuki Kimura
Ph.D. candidate, Tokyo Institute of Technology

xiangjun:
Hi Takayuki Kimura,

Please clarify your question by providing concrete examples of "pi-stack and pi-pair" in relation to SNAP output.

Thanks,

Xiang-Jun

akakios:
It is about the two sections around the end of SNAP outputs Like below:
Pairs and stacks. Thank you.

****************************************************************************
List of 7 base/amino-acid pairs
       id   nt-aa   nt           aa      vertical-distance   plane-angle
   1  1oct  A-gln  A.DA204      C.GLN44         0.05             
****************************************************************************
List of 2 base/amino-acid stacks

xiangjun:
The base/amino-acid pairs identified by SNAP are named pseudo pairs (see doi: 10.1093/nar/gkr452). I have never heard of the term "pi-pair" as used in the your initial message. So I was confused as to what it really means.

Using 1oct as an example, a graphical illustration of the A-gln pseudo-pair (A.DA204 and C.GLN44) is attached. It should be clear that it is indeed like a base pair (H-bonds, coplanar).

Please generate a similar graph of a base/amino-acid stacking interaction and post it back. This way you would better understand the differences between the DSSR output sections on pair vs stack. It also helps other viewers of the thread.

Best regards,

Xiang-Jun

akakios:
Thank you for the clarification. Stack example is like the following:

***************************************************************************
List of 2 base/amino-acid stacks
       id   nt-aa   nt           aa      vertical-distance   plane-angle
   1  1oct  T-gln  A.DT203      C.GLN44         3.79              1
   2  1oct  G-arg  B.DG225      C.ARG105        3.31       

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Created and maintained by Dr. Xiang-Jun Lu [律祥俊] (xiangjun@x3dna.org)
The Bussemaker Laboratory at the Department of Biological Sciences, Columbia University.