“Molecular scissors” for plastic waste

A research team from the University of Greifswald and Helmholtz-Zentrum-Berlin (HZB) has solved the molecular structure of the important enzyme MHETase at BESSY II.

MHETase was discovered in bacteria and together with a second enzyme – PETase – is able to break down the widely used plastic PET into its basic building blocks. This 3D structure already allowed the researchers to produce a MHETase variant with optimized activity in order to use it, together with PETase, for a sustainable recycling of PET. The results have been published in the research journal Nature Communications.

Plastics are excellent materials: extremely versatile and almost eternally durable. But this is also exactly the problem, because after only about 100 years of producing plastics, plastic particles are now found everywhere – in groundwater, in the oceans, in the air, and in the food chain. Around 50 million tonnes of the industrially important polymer PET are produced every year. Just a tiny fraction of plastics is currently recycled at all by expensive and energy-consuming processes which yield either downgraded products or depend in turn on adding ‘fresh’ crude oil.

>Read more on the BESSY II at HZB website

Image: At the MX-Beamlines at BESSY II, Gottfried Palm, Gert Weber and Manfred Weiss could solve the 3D structure of MHETase.
Credit: F. K./HZB

The quest for better medical imaging at MAX IV

Advances in the world of physics often quickly lead to advances in the world of medical diagnostics. From the moment Wilhelm Röntgen discovered X-rays he was using them to look through his wife’s hand.

A lot of the physics principles at the foundation of MAX IV are also at the foundation of medical imaging technologies such as nuclear magnetic resonance imaging, x-ray computed tomography and positron emission tomography.
Positron emission spectroscopy is more commonly known as PET imaging. It’s a method used to study metabolic processes in the body as a research tool but also to diagnose disease. An important use today is in the diagnosis of metastases in cancer patients, but it can also be used to diagnose certain types of dementia.

In PET, a positron-emitting radionuclide is injected into a patient and travels around the body until it accumulates somewhere, depending on the chemical composition. For example, the fluorine-18 radionuclide when bound to deoxyglucose accumulates in metabolically active cells which is useful for finding metastases. The radionuclide is unstable and emits positrons which is the antimatter equivalent of an electron. When a positron and an electron inevitably meet, they annihilate one another, producing two pulses of gamma radiation traveling in opposite directions. By placing a detector around a patient, it is possible to measure the gamma radiation and convert the signal into something that can be more easily measured. These detectors are made up of materials known as scintillators which take high energy radiation and emit lower energy radiation that can be detected using fast photodetectors – photomultiplier tubes.

>Read more on the MAX IV Laboratory website