# Refined interface - restraint file

**URL:** <https://ask.bioexcel.eu/t/refined-interface-restraint-file/2525>\
**Category:** Uncategorized\
**Created:** [October 28, 2020, 11:08am UTC](https://ask.bioexcel.eu/t/refined-interface-restraint-file/2525 "2020-10-28T11:08:50Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![jonas.emsley](https://avatars.discourse-cdn.com/v4/letter/j/b9e5f3/32.png) [@jonas.emsley](https://ask.bioexcel.eu/u/jonas.emsley)\
**Post date:** [October 28, 2020, 11:08am UTC](https://ask.bioexcel.eu/t/refined-interface-restraint-file/2525/1 "2020-10-28T11:08:50Z")

</div>

DearAll  
I have pairs of amino acids from an interface and i want a refined docking. How do i specify these restraints for pairings in haddock? i.e. create a  
AIR restraint file  
an input it  
cheers  
jonas

---

<div class="post-metadata">

**Author:** ![amjjbonvin](https://dub1.discourse-cdn.com/flex013/user_avatar/ask.bioexcel.eu/amjjbonvin/32/23_2.png) [@amjjbonvin](https://ask.bioexcel.eu/u/amjjbonvin)\
**Post date:** [October 28, 2020, 1:49pm UTC](https://ask.bioexcel.eu/t/refined-interface-restraint-file/2525/2 "2020-10-28T13:49:17Z")

</div>

You can define a distance restraint between those two residues and upload it as unambiguous restraints

E.g.

assign (segid A and resid 100) (segid B and resid 200) 2.0 2.0 0.0

This will define a distance restraint between residue 100 of chain A and residue 200 of chain B.  
The upper limit is 2A in this case, which will enforce some atom contacts should be made.

See also: [https://www.bonvinlab.org/software/bpg/restraints/#unambiguous-interaction-restraints](https://www.bonvinlab.org/software/bpg/restraints/#unambiguous-interaction-restraints)