Screening assay transfer and development

Protéus has a considerable experience in screening protein libraries. Using our platform and our proprietary technologies, we have identified dozens of proteins, especially enzymes with targeted performances, either from biodiversity libraries or from directed evolution libraries.

You can take advantage of these unique capabilities for identifying improved variants of your own genes.
As your protein is unique, our screening services are customised according to your needs and the performances to be achieved. We will be happy to design a custom screening strategy for you.


Various cases can be considered:

• If you have a screening assay, Protéus will transfer the assay to our own platform and then perform the screening
• If you don’t have any screening assay, Protéus will review the options for screening the protein and develop a strategy for implementing this screening.

Transfer of your screening assay

If you have a screening protocol for your protein, but you don’t have the screening capacity, Protéus will transfer your protocol to our own platform.

The protocol will be tested on our platform for the wild-type protein. The objective is to set the standards for screening with limited inter and intra-plate variations.

Following this step, Protéus will be able to precisely evaluate the screening throughput that can be achieved.

Development of a custom library screening assay

When no screening assay is available, Protéus can develop a protocol to meet your protein optimisation objectives.

An initial strategic study, based on the litterature, will first be performed in order to identify the different possible strategies that could be applied for high throughput screening. For each approach identified by Protéus as a possible screening assay, we will design an experimental plan and provide an estimation of the required equipment, time, and budget.

• Develop a robust assay for hit detection
• Transfer and validate your assay in HTS conditions

• dedicated class 1000 clean rooms
• robotics (colony picking, cherry picking, liquid-handling devices)
• plate reading devices (colorimetry and fluorescence)
• a routine throughput of 20,000 assays per day for colorimetric readout
• 2000 HPLC-based screens per week
• Proprietary CLIPS-O™ substrates
• Integration with protein expression and engineering capabilities

• the activity you want to screen for and the final application
• the substrates used in application or for screening
• existing assays...

A report including:

• bibliographic study
• QC data
• Assay validation data

Evolution of a therapeutic protein - development of a customised binding screening assay

Tumor Necrosis Factor (TNF) is a primary mediator of the inflammatory response. Excessive levels of circulating TNF are associated with inflammatory diseases such as rheumatoid arthritis. Accordingly, the use of soluble receptor to capture circulating TNF and block its action is a possible therapeutic strategy.

The objective of Protéus was to enhance the binding efficacy of TNF-R1 to TNF using our protein evolution platform.

A single L-Shuffling™ round was implemented, using TNF-R1 and a related gene as parental genes. The recombinant genes were then expressed in vitro using Phenomics™ cell-free expression technology.

To screen for improved binders, Protéus has developed a dedicated assay based on fluorescence transfer. Due to the complexity of the screening method, a sample of less than 600 mutants were screened.

This screening method enabled the identification of significantly improved variants, with up to 3-fold increased binding efficacy when compared to the wild-type gene.

Approximately two thirds of the shuffled variants tested were active. L-Shuffling™ generally provides libraries with a high frequency of active clones. This feature is particularly advantageous in the case of biopharmaceuticals for which the screening assays may be complex and not easily amenable to high throughput.