Enzyme Fragment Complementation Assay Technology

Enabling Technologies with a Flexible Platform

Eurofins DiscoverX® offers patented Enzyme Complementation Technology (EFC) technology providing drug discovery and development researchers the means to interrogate biomolecular reactions for advancing therapeutic drug screening and development programs. EFC is a homogeneous detection assay system that enables you to measure and rank ligand potencies, discover the mechanism of action (MOA), perform binding and functional screens, identify novel compounds, and much more.


As a robust and reliable assay technology, EFC has been used for decades to generate Eurofins DiscoverX cell-based platforms such as PathHunter®, KILR®, InCELL, and HitHunter®. These assay formats are used for both the discovery and the commercial release of many small molecule drugs and biological therapeutics on the market today and many more to come.


Capabilities Brochure Products Targets list



Directly Measure Relevant Target Biology with Ease

  • Homogenous Format — Add-and-read assay format without the need for washing, centrifugation, or filtration
  • Robust — Enzymatically-amplified assays with large signal-to-background ratios and high precision with Z' factors > 0.7 and lot-to-lot reproducibility
  • Qualified and Validated — Extensively optimized for hundreds of targets used for screening billions of data points, and cited in thousands of peer-reviewed publications
  • Scalable — Easily scalable and HTS-friendly from 96- to 3456-well microplate format

Highlights of EFC-Based Assays

Homogenous Sensitive Detection Robust Luminescence Readout Easy to Transfer
  • Simple add-and-read assay format
  • No media change, shaking, or filtration
  • Enzymatically-amplified assay
  • High precision & accuracy
  • Large dynamic range
  • High assay reproducibility
  • Easily quantified luminescence readout
  • Compatible with most readers
  • Assay protocol is similar across the platform
  • Detailed user manuals

Over 1,000 Available Functional Assays for Popular Target Classes

Over 1000 Available Functional Assays for Popular Target Classes

EFC Applications

EFC Technology Principle

EFC Technology Principle

EFC is based on two recombinant β-galactosidase (β-gal) enzyme fragments that act as an enzyme acceptor (EA) and an enzyme donor (ED). Separately, the fragments are inactive, but when combined, they form an active β-gal enzyme that hydrolyzes its substrate to produce a chemiluminescence signal.

Assay Platforms for Your Modality and Stage of Development

Assay Platforms for Your Modality and Stage of Development