# Protein-peptide free energy approximation

**URL:** <https://gromacs.bioexcel.eu/t/protein-peptide-free-energy-approximation/2809>\
**Category:** User discussions\
**Created:** [September 13, 2021, 8:57pm UTC](https://gromacs.bioexcel.eu/t/protein-peptide-free-energy-approximation/2809 "2021-09-13T20:57:31Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Mirrty](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@Mirrty](https://gromacs.bioexcel.eu/u/Mirrty)\
**Post date:** [September 13, 2021, 8:57pm UTC](https://gromacs.bioexcel.eu/t/protein-peptide-free-energy-approximation/2809/1 "2021-09-13T20:57:31Z")

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GROMACS version: 2021.3  
GROMACS modification: Yes/No

Hey,

I am a bit new to MD, and I have a task of ranking few complexes with the same protein but different small peptides. I would like to know, what tools there are in Gromacs to provide an approximate evaluation of protein-peptide binding affinity?

Thanks,  
++