Scientists at the Technical University of Munich (TUM) have developed a method that relies on physics rather than conventional chemistry to obtain proteins. Using short-wave, UV light invisible to humans, they have succeeded in purifying proteins from cell extracts or cultures. This method is more efficient and gentler than existing techniques and could be used in the future for high-throughput drug development in pharmaceutical or biotechnology companies.
Proteins play a key role in the life sciences — from basic research and biotechnological applications to the development and manufacturing of pharmaceuticals. Scientists engaged in molecular biology or molecular medicine require proteins in their pure form for various purposes, to serve for investigation or as active substances. Such proteins are isolated from natural sources or produced with the help of genetically modified cells.
For the past 50 years, the standard method has been affinity chromatography, which comes with a significant drawback: the purified target protein can be damaged during the final purification step. The team led by Arne Skerra, Professor of Biological Chemistry at TUM, instead employs a physical mechanism rather than chemical reagents.
The newly developed method utilizes a chromatography column filled with a porous carrier material. What sets it apart, however, are the LED lights arranged around the column and a small molecular tag attached to the target protein. This minimalist tag, called the Azo tag, was developed by Peter Mayrhofer, Markus Anneser, and Stefan Achatz together with Arne Skerra at the Chair of Biological Chemistry. It is based on the light-sensitive chemical group "azobenzene." The tag can change its shape when exposed to specific light, acting like a molecular anchor that allows the target protein to bind highly specifically to the carrier material within the chromatography column.
When the LED lights are switched on and the column is exposed to mild UV light at a wavelength of 355 nanometers, the attached tag changes its shape, allowing the target protein with the azo tag to be washed out of the column in a pure, concentrated, and intact form. Isolated in this manner, the protein can be used directly for further studies — without additional purification steps.
The researchers now use the method regularly and have already been able to purify antibodies against breast cancer. A patent application has now been filed for the process. One of their goals is to automate the procedure to make it even more efficient, enabling its use in high-throughput drug development within pharmaceutical or biotechnology companies.