A tape recorder for the synchrotron

Non-stop: A new method makes it easier to obtain snapshots of fast reactions or to analyze fragile protein structures using X-ray scattering. This serial crystallography is made possible by a kind of cassette player: A perforated polymer tape serves as a sample carrier that transports the proteins or other biochemical samples past the X-ray beam. This makes a kind of “stop-motion” recording of dynamic processes possible.

Whether it’s the structure of proteins, the course of chemical reactions or the secrets of water molecules : today, researchers often gain insights into the realm of molecules with the help of X-ray lasers and other high-precision X-ray sources. In order to elucidate the structure of a protein or an exotic crystal, for example, the samples are illuminated with this radiation and the resulting scattering pattern is analyzed.

However, in order to use X-ray crystallography to record the three-dimensional structure of a sample crystal or to capture dynamic processes, images from all angles are required, which means that the sample in the synchrotron beam has to be changed, which is time-consuming.

A tape drive for crystals

A new device that literally transports samples non-stop into the synchrotron can help. The “Blotting Tapedrive” developed by researchers at the Technical University of Lübeck works in principle in a similar way to a cassette player: a perforated polymer tape runs through the X-ray beam in constant motion. In front of the beam, the belt is continuously loaded with fresh microcrystals of the sample substance.

Just before the X-ray zone, a second belt scrapes off the solution liquid. As a result, only the “naked” crystals of the sample substance remain in the holes in the tape, which can now be illuminated by the intense X-ray beam. In a first application test, the new blotting tape drive is now being installed in a beam path of the European Synchrotron Radiation Facility (ESRF) in Grenoble, the largest electron synchrotron in Europe.

Installation at the European X-ray synchrotron

Scientists can now use the blotting tape drive to “film” molecular processes or to capture three-dimensional structures of crystals in one measurement run with the help of dynamic snapshots recorded in quick succession. The team at TH Lübeck is already using it to plan analyzes of various proteins and their reactions.

“Our goal is to investigate time-resolved structural changes induced by light activation, ligand mixing or pH jumps in the crystallized proteins very quickly and with a high signal-to-noise ratio,” explains Mia Lahey-Rudolph from the Lübeck University of Applied Sciences. This not only provides new insights into biology, but can also form the basis for the development of tailor-made drugs, for example.

Source: Technical University of Lübeck