Nav: Home

Tailor-made synthesis of cyclic chemicals by means of enzymes

May 16, 2018

Penicillin-based antibiotics contain a five-membered hydrocarbon cycle, additionally incorporating a sulfur and a nitrogen atom. Nadine Zumbrägel, doctoral student at the Chair of Organic Chemistry I at Bielefeld University, has succeeded in selectively synthesizing this important substructure with different residues on this cycle using a biotechnological method. The targeted design of such structures now enables the preparation of substance libraries of such so-called heterocycles, which can in future be used by the pharmaceutical industry to find new active substances. Besides the Bielefeld chemists, two scientists from the Ruhr-University Bochum were also involved in the studies. The researchers present their findings today (16 May 2018) in the renowned journal Nature Communications with Zumbrägel as first author and Professor Dr. Harald Gröger, head of the Chair of Organic Chemistry I, as corresponding author.

Recently, in the renowned specialist journal "Chemical & Engineering News", antibiotics were described as one of the nine ways chemistry has changed the world. Of particular importance are penicillins, which in turn contain a five-membered hydrocarbon cycle with a sulfur and a nitrogen atom additionally incorporated therein. The selective production of this important substructure, flexibly equipped with different substituents on the cycle, in turn represents a substance library for finding new drug structures. In principle, access to these cyclic structures is conceivable from easily accessible substrates, the so-called 3-thiazolines. The cyclic structure is already pre-formed and "only" one double bond has to be converted into a single bond by means of a reduction.

Although these 3-thiazolines have been known for decades and were first reported in the 1950s, this conversion proved to be synthetically difficult. This is remarkable since a large number of chemical methods are generally available for the reaction type of reduction and have already been successfully used for numerous synthesis purposes. There are several reasons why such "classical chemical" processes proved ineffective in the production of this compound class of five-membered cycles with incorporated sulfur and nitrogen atoms: for instance, strongly reducing processes lead to undesired ring-opening and in other reduction processes with metal catalysts, the sulfur contained in the cycle acts like a catalyst poison. The required selectivity also proved to be an insurmountable hurdle: during reduction, chiral compounds can form, which behave like image and mirror image. For active substances it is important that only one of these forms, so-called enantiomers, is present. Previous methods were able to preserve the ring in the best case, but resulted in only extremely low selectivities.

In her doctoral thesis funded by the German Federal Ministry of Education and Research (BMBF) as part of the "Biotechnology 2020+, Next Generation of Biotechnological Processes" funding programme, Nadine Zumbrägel has now succeeded for the first time in reducing 3-thiazolines without side reactions to the desired target compounds in a highly selective manner, forming only one enantiomer. For this purpose, she used representatives of the enzyme class of the so-called imine reductases as biocatalysts. Zumbrägel explains: "The pharmaceutical industry is increasingly demanding highly enantioselective synthesis methods. One possibility is the use of enzymes as suitable catalysts, which are reaction accelerating molecules in chemical processes."

The researchers also succeeded in extending the reduction method to other sulphur-containing heterocycles, thus developing a platform technology. The applicability of this reduction method has also already been demonstrated by the scientists on an enlarged laboratory scale. "This successful combination of biotechnology and heterocyclic chemistry is a further proof for the potential of enzymes as natural catalysts for use in preparing chemicals," says Gröger, who has been conducting research on biocatalytic processes for the synthesis of industrial chemicals with his research group at Bielefeld University since 2011. In cooperation with Professor Dr. Stefan Huber from the Ruhr-University Bochum, who carried out quantum mechanical calculations, it was also possible to rationally reproduce the experimental observations with the aid of computer chemistry. Dr. Christian Merten, likewise from the Ruhr-University Bochum, also combined quantum mechanical calculations with VCD (Vibrational Circular Dichroism) measurements, which enabled the determination of the stereochemical properties of the target compound.
-end-
Original publication: Nadine Zumbrägel, Christian Merten, Stefan M. Huber, Harald Gröger, Enantioselective reduction of sulfur-containing cyclic imines through biocatalysis, Nature Communications, DOI: 10.1038/s41467-018-03841-5, published on the 16th of May 2018.

Further information is available online at:

Website Organic Chemistry I, link: http://www.uni-bielefeld.de/chemie/arbeitsbereiche/oc1/HG/

Press release (8/1/2018) "Enzyme für umweltfreundliche Chemie nutzen" (in German) ["Using en-zymes for green chemistry"], link: https://ekvv.uni-bielefeld.de/blog/uniaktuell/entry/enzyme_f%C3%BCr_umweltfreundliche_chemie_nutzen

Contact:
Professor Dr. Harald Gröger, Bielefeld University
Faculty of Chemistry, Organic Chemistry I
Telephone: 0049 521 106-2057, -6920 (secretary's office)
Email: harald.groeger@uni-bielefeld.de

Bielefeld University

Related Sulfur Articles:

Using high energy density material in electrode design enhances lithium sulfur batteries
To develop higher capacity batteries, researchers have looked to lithium sulfur batteries because of sulfur's high theoretical capacity and energy density.
Earth, wind, flora sway Trinidad sulfur levels
UC geologists get a glimpse into the power of wind, rain, coastal proximity and climate on coastal environments.
New study tracks sulfur-based metabolism in the open ocean
Oceanographers found that marine microbes process sulfonate, a plentiful marine nutrient, in a way that is similar to soils.
Zero-emission diesel combustion using a non-equilibrium-plasma-assisted MnO2 filter
A Japan-based research team led by Kanazawa University have used ozone from an atmospheric-pressure non-equilibrium plasma together with the desulfurization catalyst MnO2 to almost completely eliminate NOx and SOx from diesel exhaust gas at a low temperature of 473 K.
2018's biggest volcanic eruption of sulfur dioxide
The Manaro Voui volcano on the island of Ambae in the nation of Vanuatu in the South Pacific Ocean made the 2018 record books.
More Sulfur News and Sulfur Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...