Just a tiny shift of electrons can decide whether the patient leaves the hospital unharmed or with an amputated leg after routine knee surgery.

A drastic example, admittedly, but a sometimes true one when it comes to multidrug-resistant bacteria.

Even reserve antibiotics that are related to penicillins can no longer do anything against them.

Their weapon, a molecular beta-lactam ring with which they prevent a bacterium from building its cell wall, has become ineffective.

The resistant pathogens have an enzyme from the group of beta-lactamases that cuts the lactam ring and thus disarms the antibiotic.

This is exactly what happens with the subtle shifting of electrons.

In order to understand how the enzyme works,

you have to watch his actions in detail and in slow motion, similar to the video analysis of a shot on goal hidden in the penalty area.

If this succeeds, research could develop new, more effective antibiotics in a targeted manner.

Unfortunately, the magnification of a light microscope cannot simply be turned up until the activity of the biomolecules becomes visible with atomic precision.

With wavelengths of hundreds of nanometers, light waves are far too long for this.

They are just as unimpressed by small molecular building blocks as the sea swell is by a swimming seagull.

Typical atomic diameters are around a thousand times smaller than light waves.

Although many biomolecules are giants, if you want to get behind their activities in the living organism, you have to be able to "zoom" down to the atoms and electrons.

Then you could even watch the enzymes of multi-resistant germs cut up lactam rings.

"In many cases, these shifts are smaller than the diameter of an atom, maybe half a tenth of a nanometer," explains Marius Schmidt.

The German biophysicist from the University of Wisconsin in Milwaukee is one of the pioneers of "filming" molecular processes.

What fascinates him about proteins is their importance for life functions such as thinking, feeling, tasting, smelling, seeing or muscular movements.

And most proteins are enzymes.

"As biocatalysts, for example, they convert the energy from ingested food into various other forms of energy."

But enzymes can also be weapons.

The beta-lactamases, for example, are part of the arsenal of many bacteria that can make us ill, including Mycobacterium tuberculosis, whose enzymatic attack on the antibiotic ceftriaxone Schmidt was recently able to “film” in slow motion and in detail as part of an international collaboration.

Because there are many different beta-lacatamases, it is worth targeting this family of enzymes.

After all, behind the molecule film production is a gigantic effort.

But which camera makes such shooting possible?

At the speed of light through a magnetic slalom course

First of all, sufficiently short-wave light is required: X-ray light.

It must also be extremely hard.

This is what X-ray lasers offer.

They have been in development since the 1970s and are now gradually becoming available.

Conventional laser technology does not work with X-rays.

Rather, the hard X-ray light is generated using a large electron accelerator, the technology is called a free-electron laser (FEL).

The first X-ray laser, the Linac Coherent Light Source (LCLS) in Stanford, started work in 2009, and in 2017 the world's most powerful X-ray laser went into operation with the European XFEL in Hamburg.

Like the LCLS, the core of the XFEL consists of a linear accelerator, i.e. a straight acceleration section.