Proteins on the Stretching Rack

When proteins change their fold, this can lead to fatal consequences. Scientists of a European research network are looking for new methods to predict and control the behavior of these molecules. Pharmacologists of the University of Würzburg take part in the project.

Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis - all these diseases are due to the same cause: In the brain of the patients, millions of incorrectly folded proteins clot into non-recyclable clumps, destroying the nerve cells in the process. Proteins that go off-course in arranging themselves into complex three-dimensional structures are suspected to be the trigger factors of several further diseases, such as cancer, diabetes or atherosclerosis.

Dangerous structures

Such incorrectly formed structures that are dangerous to humans can come from an unexpected quarter where the layman would generally not suspect any danger - quite the contrary. "New agents in medicine might also fold incorrectly in the patient's body, causing dangerous side effects, possibly even an allergic reaction, which can prove fatal," explains Dr. Tessa Lühmann.

The biochemist is a research scientist of the Department for Pharmaceutics and Biopharmacy at the University of Würzburg. Over the coming three years, she is going to develop methods for predicting and ideally even preventing the undesired behavior in a new EU-funded project. The project includes scientists from Zurich, Istanbul and Barcelona as well as representatives of the industry.

Search for new agents

Antibodies: Proteins of this type will be studied by Tessa Lühmann and her colleagues over the next few years. They are increasingly used in medicine as a vaccine or agent against cancer and autoimmune diseases. For this purpose, it is vitally important that these proteins remain stable and do not suddenly change their folding status. However, such changes are not that unlikely: "The proteins can change in structure, for instance, when they are subjected to high shear forces during injection, when the pH value of the environment changes or simply when they are stored for a period of several years," says Lühmann. "From a business perspective", this can be very frustrating for manufacturers who have invested a lot of money in the development of such drugs.

Therefore, the scientists intend to develop a new method which allows them to quickly draw conclusions about the behavior of proteins in special environments under defined conditions. Their approach: They take an individual molecule, fix it in a special setup and then stretch it, varying the relevant environmental conditions, such as temperature and pH value. "The force required to unfold the proteins allows us to draw inferences on the stability of these molecules in their respective environment," the biochemist explains. In this way, the pharmaceutical industry can get informed at an early stage as to whether and under which conditions a protein tends to assume an undesired structure.

Magnetic nanotubes as docking sites

Magnetic nanotubes are a central part of the new technology. Only a few millionths of a millimeter in diameter, they provide targeted docking sites for the protein structures. Due to their magnetism, these rods can be moved and put into a desired position with high precision in a magnetic field. The tip of an atomic force microscope serves as a second connection point for the protein. Connected at two points, the protein can be unfolded and the required force can be exactly determined.

The production of the nanotubes is the responsibility of the scientists at ETH Zurich, who are familiar with the tiny magnetic rods. The measurements are carried out at Istanbul University, where the experts for the technical part of the work are located. Lühmann's doctoral student, Joel Wurzel, will always be present on location as well.

The Würzburg contribution

And where does Würzburg come in? "We are the biologically oriented pharmaceutical technologists of the research network," says Tessa Lühmann. In the laboratories at the Hubland Campus, the relevant proteins are selected and then connected to the nanotubes. The Würzburg scientists also define the conditions for the measurements.

The European Union funds the Manaqa project - Magnetic Nano Actuators for Quantitative Analysis - with € 2.7 million; the University of Würzburg receives € 200,000. The project duration is three years. "The construction of the nanotubes is a complex process. It will probably take a year until we are able to connect the proteins," says Lühmann. The measurements shall take place at the end of 2013 - if everything goes smoothly.

Source: University of Würzburg