Protein expression

Expression in E.coli - Screening service

If you wish to carry out protein expression in E. coli, the facility provides a screening service to help you identify successful expression conditions. A series of plasmids and bacterial strains are available for this purpose.

The plasmid of choice will be used to carry out a preliminary test in a small culture volume (10 ml) using standard conditions (Rosetta 2 pLysS/BL21 pLysS at 18°C, in autoinduction medium).

If soluble protein is detected, further optimization will be carried out. In case of a negative outcome alternative strategies can be explored (e.g. use of a different tag, refolding, co-expression with a protein partner, etc.). Results of expression tests will be further confirmed by western blot upon request.

The screening service is currently available only for proteins fused to the His tag (alone, or in combination with another tag). Cloning is not included in the service.

For further details, please contact Patrizia Di Crescenzio.


The facility runs as a non-for-profit service. Charges cover the cost of consumables:

  • Screening service: £10 per test (1 test is 1 construct expressed in a specific combination of conditions – bacterial strain/temperature/medium)
  • Western blot with anti-His antibody: £35 per western blot (each western can fit up to 10 samples)
  • Scaled up bacterial culture: £2 per litre