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Fast Free Energies Predictions

Discover drugs with speed and ease using the OpenEye Affinity (OE Affinity) set of tools designed to accurately estimate binding free energies.

With a focus on cutting-edge science and technology, OE Affinity simplifies the process of drug discovery by delivering powerful tools directly to your web browser on Orion® cloud modeling platform. There's no software to install; all you need is a web browser. Simply log in and get started!

OpenEye’s Affinity tools let you calculate binding free energies, with accuracy and speed. Scientists can access the automated process conveniently from their web browsers.


  • Proven. Adapted from published work from the DeGroot Lab at Max Planck Institute
  • Accurate. Validated on internal and external datasets
  • Flexible. Edge mapper options for connecting ligands ncluding OELOMAP, Single-hub Star Map, and Binary Star Map.
  • Easy-to-Use. Quickly get up and running in a familiar Orion web-based environment
  • Automated. Simple process from system set-up, end-point equilibration, and free energy calculation
  • Performance. Extremely fast and highly parallelizable; run an entire ligand dataset in a few hours
  • Control. Highly customizable for novice use and expert control
  • Integrated. Easily combine with other ligand- and structure-based methods

Rooted in Science, Optimized for Performance, Made for You

OpenEye delivers efficient and effective solutions to estimate binding free energies of protein-ligand complexes. Various options to suit your needs:

  • OE SZYBKI: An extremely fast approach to perform force field energy evaluations or geometry optimizations on small molecule ligands or protein-ligand complexes
  • OE Affinity Scoring: A fast, more approximate option that combines physics- and knowledge-based scoring. Automated for ease-of-use, OE Affinity Scoring provides you with quick relative binding free energy estimates from short-trajectory molecular dynamics (MD) trajectories
  • OE Affinity Relative Binding: A robust and accurate thermodynamic method to calculate relative binding free energies. Adapted from the Non Equilibrium Switching (NES) work published from the Max Planck Institute, OpenEye has improved the methodology and performance.

Our comprehensive solution ensure you get the benefit of speed, performance, and accuracy while saving time and money.

OE Methods for Binfing Affinity Image
OpenEye offers automated, turn-key scientific solutions for various methodologies to meet all your binding affinity prediction needs.
OpenEye's Induced Fit Posing yields intuitive results that assist scientists in selecting high-quality candidates. An illustrative example is provided for its results against the CDK2 protein target.
Schematic depiction of OpenEye's Induced Fit Posing.

Induced Fit Posing

Predicting the binding of diverse ligands becomes notably challenging when adjustments are necessary in the receptor’s binding site. OpenEye’s Induced-fit posing (IFP) offers a specialized solution for accurate binding pose prediction in these scenarios. IFP predicts binding configuration of ligands that impact receptor’s binding site residue side chains. Use IFP to gain insights into the binding mechanisms of your compounds with flexible target sites and streamline selection of your lead compounds for optimization.

To enhance your ability to predict ligand binding affinity for proteins with flexible target sites, consider leveraging both IFP and OE Affinity Relative Binding. These tools combined help provide more accurate predictions of ligand-protein binding.

Download OpenEye Science Brief on Accurate Binding Pose Prediction with Induced-fit posing (IFP)

NES Automated Workflow Image
OpenEye provides a fully automated workflow to simplify your calculations; from protein-ligand preparation to analyzing Free Energies Results. The workflow is also customizable for experts use and control.


Learn More

OE Affinity can help you estimate relative binding free energies, speed up your drug-design process, and save costs by reducing failure rates.

Download OpenEye Science Brief on Affinity (Free Energy) Prediction in Structure-Based Lead Optimization

Download OpenEye Science Brief on Accurate Binding Pose Prediction with Induced-fit posing (IFP)


For science details, WATCH OpenEye’s miniWebinar recording from September 2021 on Using Non Equilibrium Switching for your Relative Binding Free Energies Calculations by Christopher Bayly, Ph.D.

And WATCH the OE Affinity Mapper feature presented by Gaetano Calabro, Ph.D, from June 2022


  1. Large scale relative protein ligand binding affinities using non-equilibrium alchemy, Gapsys et al., Chemical Science, 2020, 11, 1140-1152


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