Problem

A global pharmaceutical company was intent on using PerkinElmer’s AlphaScreen™ technology to run an important, time-sensitive kinase campaign. After the first screen, they experienced a high hit rate of 5 to 7%. They considered the hit rate to be unacceptable because it implicated a large number of secondary screening events, thus raising costs and extending deadlines. Since this was their first experience with AlphaScreen, they were unsure of the mechanisms behind the high hit rate, and how to achieve their hit rate goal of .4 to .5%. They were also under deadline pressure to screen several million compounds as quickly as possible.

Solution

As soon as the pharmaceutical researchers discovered the high hit rate, they called PerkinElmer. Within that same week, the scientists shared their data with PerkinElmer scientists, who, in turn, formulated and implemented and action plan immediately.

A key component of the action plan included having PerkinElmer send a team to work side-by-side with the researchers. The PerkinElmer team’s goal was to analyze the way the assay was performed and the order of additions of reagents and buffer components.

After conversations with scientists and analysis of the data, suspicion rapidly fell on a non-assay specific interference problem. PerkinElmer scientists were able to use a combination of AlphaScreen interference assays, using the AlphaScreen TruHits™ kit, and spectrophotometry to confirm the hypothesis and identify the actual mechanism of interference. The problem was that the company’s compound library contained a high number of water insoluble compounds. These compounds were aggregating in the assay well, causing light scattering that was quenching the AlphaScreen signal.

After some research into possible solutions, PerkinElmer discovered that the assay required more Tween-20® detergent in the detection buffer, which helps restore compound solubility. Furthermore, PerkinElmer scientists were able to reassure the chemists that Tween-20 would not interfere with their assay by creating a slight modification to the protocol to include Tween only in the detection step.

By the fourth day of working together, the research scientists were able to begin running full screens again with no problem. They then went on to run screens of 1 to 2 million compounds each. They also saved significant time and money in the secondary screening phase by being able to dismiss compounds generating non-specific signal without the need for extensive methods such as building competition curves.

The solution provided to this leading company now allows them to identify any problematic compound in their libraries and take precautions in advance of their screens.

Finally, after partnering so closely, PerkinElmer remains in regular contact with the scientists for follow-up and further collaborations on both AlphaScreen kinases and other types of assays.