# Protein-Small molecule docking problem

**URL:** <https://ask.bioexcel.eu/t/protein-small-molecule-docking-problem/554>\
**Category:** HADDOCK\
**Created:** [October 22, 2017, 9:17am UTC](https://ask.bioexcel.eu/t/protein-small-molecule-docking-problem/554 "2017-10-22T09:17:27Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![iven\_Ma](https://avatars.discourse-cdn.com/v4/letter/i/ba9def/32.png) [@iven\_Ma](https://ask.bioexcel.eu/u/iven_Ma)\
**Post date:** [October 22, 2017, 9:17am UTC](https://ask.bioexcel.eu/t/protein-small-molecule-docking-problem/554/1 "2017-10-22T09:17:27Z")

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The HADDOCK category is meant to discuss any HADDOCK-related issue. For general information about HADDOCK refer to [http://www.bonvinlab.org/software/haddock2.2](http://www.bonvinlab.org/software/haddock2.2)

hi,

I am docking between protein and small molecule on web server using the easy interface service., for protein, it is OK.

the error read as: You must supply active and/or passive residues for your second protein.

How should I supply ‘active and/or passive residues’ for small molecule?

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**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 22, 2017, 12:10pm UTC](https://ask.bioexcel.eu/t/protein-small-molecule-docking-problem/554/2 "2017-10-22T12:10:15Z")

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Define the ligand residue number as active.

Also visit our tutorial about protein-ligand docking, especially the second stage of it:

> **[HADDOCK small molecule binding site screening](http://www.bonvinlab.org/education/HADDOCK-binding-sites/#setting-up-a-new-docking-run-targeting-the-identified-binding-pocket)**
>
> A small tutorial on identifying putative binding site for small ligands using HADDOCK