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what it does

  • accurate binding mode prediction

    For a protein with known three-dimensional structure and a small ligand molecule, FlexX4 accurately predicts the geometry of the protein-ligand complex within a few seconds. It has been validated, benchmarked and successfully used thousands of times as more than 10.000 citations of the original scientific publication[1] since 1996 impressively demonstrate.
  • virtual screening

    FlexX4 sets new records in vHTS. You can screen a library of ~1,000 compounds in less than an hour on a laptop with 8 cores. FlexX-based docking led in many application studies to superior enrichment ratios[2]. So you effectively find active compounds in large libraries. If you are screening compounds from a combinatorial library, you can take advantage of a novel pharmacophore-based combinatorial docking[3] to further gain significant speed-up and better enrichment.

what's new?

  • parallel computing

    FlexX4 has been completely re-written. It is now thread-safe, so it runs in parallel and automatically uses all cores of your computer.
  • compound series docking

    For better handling of one of the most frequent application scenarios — namely working within congeneric compound series — we equipped FlexX4 with a template-docking option (cf. below).
  • template docking... performed by determining the Maximum Common Substructure (MCS) between the template and the compound-to-dock. Based on the MCS multiple overlays are generated to preserve the binding mode of the common core.
  • fully automatic setup

    Our ground breaking Protoss technology takes the burden of proper protonation, choice of tautomer, resolution of ambiguities, ... now off of your shoulders. No more "receptor preparation" — simply dock!


What is the competitive advantage of FlexX4 over other docking software?

Outstanding with FlexX4 is:

  • docking for non-experts: the usage is child's play — particularly within the SeeSAR-interface. But also, the multitude of interfaces provide a maximum of flexibility to utilize this docker.
  • tailored solutions with pharmacophore constraints: used not only as a post-filter but as guidance to find in a vast solution space the ones which obey the constraints. This is world-wide unique.
  • best results with compound series: the novel template-, or MCS-based docking is a winning argument in this most prevalent application scenario

I already have several dockers in my portfolio. Why do I need another one?

Several years ago, docking software has been benchmarked up and down[2]. Only one thing became absolutely certain, the performance entirely depends on the target. No clear winner — one docker has its advantages here another one there. I.e. FlexX4 complements your portfolio it is no extra burden but pure added value. Read on here for numerous success stories.

What is the difference between the new FlexX4 and the one that is still available in LeadIT?

The successful FlexX docking-algorithm is still in use and has been further improved; however, the code has been completely re-written. It runs in parallel now and automatically uses all cores of your computer. Also the protein preparation is now fully automatic — you only provide a PDB and a reference compound (to determine the location of the active site). Also new/added is the template-, or MCS-based docking (cf. above).

Time is of the essence, so how fast is it really?

FlexX4 runs multi-threaded using all CPUs on your computer. On a typical PC with 8 cores screening 1000 molecules takes less than 1 hour. Searching in congeneric series — using the novel template-docking is yet faster. Literally thousands of molecules can be searched in 5 minutes. Fast enough?

citing toolname

In publications please cite FlexX with the respective version number as follows:

FlexX version 4.1; BioSolveIT GmbH, Sankt Augustin, Germany, 2019,

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FlexX (embedded in SeeSAR) (25.07.2019)
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