# Hwo to Pull Peptide from the Middle?

**URL:** <https://gromacs.bioexcel.eu/t/hwo-to-pull-peptide-from-the-middle/8199>\
**Category:** User discussions\
**Tags:** umbrella-sampling\
**Created:** [February 2, 2024, 4:43am UTC](https://gromacs.bioexcel.eu/t/hwo-to-pull-peptide-from-the-middle/8199 "2024-02-02T04:43:29Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Utsav](https://avatars.discourse-cdn.com/v4/letter/u/e19b73/32.png) [@Utsav](https://gromacs.bioexcel.eu/u/Utsav)\
**Post date:** [February 2, 2024, 4:43am UTC](https://gromacs.bioexcel.eu/t/hwo-to-pull-peptide-from-the-middle/8199/1 "2024-02-02T04:43:29Z")

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GROMACS version: 2022.6  
GROMACS modification: ?

Hi everyone,

Successfully performed pulling molecular dynamics (MD) on a peptide docked to a protein. Now seeking guidance on adjusting .mdp file for pulling the peptide from the middle. Any suggestions?

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<div class="post-metadata">

**Author:** ![hess](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/hess/32/416_2.png) [@hess](https://gromacs.bioexcel.eu/u/hess)\
**Post date:** [February 15, 2024, 8:33am UTC](https://gromacs.bioexcel.eu/t/hwo-to-pull-peptide-from-the-middle/8199/2 "2024-02-15T08:33:31Z")

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If it’s just pulling from the middle without biasing the orientation, the pull code with two groups with both COMs and a coordinate for the distance will do it. You can do steered MD by setting the pull rate or do adaptive sampling with AWH. There are tutorials for AWH.