Requirements

Drug target proposals should meet the selection criteria and the screening requirements listed below.

Selection criteria

The Screening Selection Committee  assesses proposals against three main criteria:

  • Is the target or approach novel, or is there a clear need for hits?
  • Are the target assay and supporting data of the highest scientific quality?
  • Is the assay compatible with ultra-high throughput screening (uHTS)?

Screening requirements

In addition, the proposed screening assay should meet the requirements listed in the table below and the owner should have hands-on experience with the assay.  If the assay does not fully meet the requirements, please indicate in the application form what in your opinion is needed in terms of resources and assistance to bring the assay up to standard. If you have developed a validated 96-well assay but do not have access to 384-well microtiter compatible plate readers or need advice on assay development in general, please contact the European Screening Centre. We are happy to advise on miniaturisation to 384-well format and discuss arranging a site visit for you to upgrade your assay to meet the European Lead Factory standards.

Please note that:

  • Assays in ELISA format are not eligible for submission, unless the assays can be converted to a homogenous format.
  • In case one or more assay reagents are carcinogenic or mutagenic, please search for alternatives in line with the European legal framework.
  • Kinetic measurements on the HTS system have limitations; alternatives are recommended.

Characteristic Requirement
Assay format

Demonstrated in 384-well format, 
preferably scalable to 1536-well format

Homogenous assay

No wash steps

Characterised reference

Available from partner or commercially available

Read out technology

Compatible with mix-and-measure and homogenous formats, e.g.:

  • Absorbance
  • Luminescence
  • Fluorescence intensity
  • Fluorescence polarization
  • Fluorescence resonance energy transfer (FRET)
  • Time resolved Fluorescence (TRF)
  • Homogeneous Time Resolved Fluorescence (HTREF /TR-FRET)

Or alternatives that give highly specific readouts (e.g. AlphaScreen technology, fluorescence lifetime, fragment complementation or FLIPR for calcium readout)

Signal / Background (S/B)
in 384-well plate format
Max assay end volume 30 µl

Sample end concentration 10-5 M

Ideally > 3 or higher

Z' (Z prime)

in 384-well plate format

Max assay end volume 30 µl

Sample end concentration 10-5 M

> 0.6

DMSO tolerance

Minimal tolerance 0.5 % DMSO

Stability of each reagent Stable for at least 8 hours
For proteins: proven freeze-thaw cycle stability
Cell lines

Certified mycoplasma free 
Stable cell lines available for transfer

Certified mycoplasma free 
Stable cell lines available for transfer

CV <10% across plate filled with reference compounds

Protein

Recombinant protein at least 80 % pure

Commercially available or feasible to produce on milligram scale (construct and protocol available for transfer)

Incubation times

Up to 4 hours

Readout stability For at least 1 hour
Experience Hands on experience in running the assay
Experimental data

Experimental data available

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Calculating your Z' alias Z prime alias Z-factor

Please note that Z prime should not be confused with Z-score or Z-value!

The Z-factor is an attempt to quantify the suitability of a particular assay for use in a full-scale, high-throughput screen.
The Z-factor is defined by four parameters: the means (µ) and standard deviations (σ) of both the positive (p) and negative (n) controls.

Z' alias Z prime alias Z-factor

not to be confused with Z-score or Z-value!

The Z-factor is an attempt to quantify the suitability of a particular assay for use in a full-scale, high-throughput screen.

The Z-factor is defined in terms of four parameters: the means and standard deviations of both the positive (p) and negative (n) controls (µp, σp and µn, σn).