Biocatalysis

Bioreactor (fermenter) on a laboratory scale

As Biocatalysis is an implementation and acceleration or steering chemical reactions ( catalysis ) designated in the enzymes as biological catalysts are used. Enzymes consist entirely or predominantly of one or more proteins and sometimes also a cofactor . Most biochemical reactions in living things are catalyzed by specific enzymes.

In technical applications at the onset of biocatalysis ( Biotechnology ) are enzymes , either isolated or in the living cell to the catalysis of chemical reactions used. It is a young field in the intersection of biotechnology and chemistry .

The terms bioconversion and biotransformation are occasionally used as synonyms for the term biocatalysis . Sometimes, however, a distinction is also made between biocatalysis as an umbrella term for all enzyme-catalyzed biochemical reactions, while the other two terms are used for enzyme-catalyzed reactions in technical applications (biotechnology).

history

Fermentation tanks for winemaking

When brewing , one example of biocatalysis, is one of the oldest known chemical processes of mankind. Biocatalytic processes using bacteria , yeasts or fungi have been known for centuries , especially in the production of wine, beer, cheese and other foods. Biocatalytic processes have also been used in the pharmaceutical industry for a long time.

This is partly about the implementation of reactions that cannot be carried out otherwise and partly about the replacement of existing syntheses with toxic reagents and solvents. In the interests of sustainability , these are being replaced by milder methods, because biocatalysts often work in water and at 20 to 40 ° C.

Examples of economically important biocatalytic processes are the production of vitamin C , the aspartame -production, the saccharification of starch to glucose syrup and the antibiotics -production by enzymatic cleavage of penicillin G .

Advantages of biocatalysis

Bioreactor for the bacterial production of vaccines

The advantages of biocatalysis for organic synthesis lie primarily in the selectivity, which is a prerequisite for achieving a high yield. Enzymes offer advantages in terms of chemoselectivity , regioselectivity , diastereoselectivity, and enantioselectivity .

Enzymes often react under mild conditions, so that only one functional group reacts under given reaction conditions. This also means that the products of biocatalytic processes are often purer and the separation of by-products is less problematic.

Due to the complex structure of enzymes, they often catalyze regio- and diastereoselective reactions. The chirality of the enzyme, which is often present, can be transferred to the prochiral substrate for the production of enantiomerically pure components in various reactions . These components are particularly popular as chiral building blocks in the manufacture of pharmaceuticals and active ingredients in agrochemicals.

The mild reaction conditions, the use of water as a solvent in many reactions and the biodegradability are reasons for intensive research into biocatalysis.

Directed evolution and rational protein design are successful methods for improving enzymes for biocatalysis .

Asymmetric biocatalysis

Two basic methods can be distinguished in asymmetric biocatalysis; on the one hand the kinetic resolution and the biocatalytic asymmetric synthesis.

In kinetic resolution, a racemate is converted with the help of enzymes. Due to the chirality of the enzymes, one enantiomer in the racemic mixture reacts faster under biocatalysis to the target product, while the other does not react.

Biocatalytic asymmetric synthesis is a reaction in which a prochiral component is converted enantioselectively into a chiral one, for example in the enantioselective reduction of ketones by yeast.

literature

AS Bommarius and BR Riebel: Biocatalysis - Fundamentals and Applications . Wiley-VCH, Weinheim 2004, ISBN 978-3527-30344-1
Garabed Antranikian : Applied Microbiology , 1st edition, Springer-Verlag Berlin Heidelberg 2006, ISBN 3-540-24083-7
GE Jeromin and M. Bertau: Bioorganikum - practical course in biocatalysis . Wiley-VCH, Weinheim 2005, ISBN 3-527-31245-5

Web links

Individual evidence

^ T. Anthonsen: Reactions Catalyzed by Enzymes. In P. Adlercreutz. P. and AJJ Straathof (Eds.): Applied Biocatalysis , 2nd Edition, Harwood Academic Publishers 1999, pp. 18-53.
^ K. Faber: Biotransformations in Organic Chemistry , 4th edition, Springer-Verlag Berlin 2000.
↑ Jayasinghe LY, Smallridge AJ, and Trewhella MA: The yeast mediated reduction of ethyl acetoacetate in petroleum ether . In: Tetrahedron Letters . 34, No. 24, 1993, p. 3949. doi : 10.1016 / S0040-4039 (00) 79272-0 .
↑ Manfred T. Reetz : Biocatalysis in Organic Chemistry and Biotechnology: Past, Present, and Future , J. Am. Chem. Soc. 135 (2013) pp. 12480-12496.

[1] T. Anthonsen: Reactions Catalyzed by Enzymes. In P. Adlercreutz. P. and AJJ Straathof (Eds.): Applied Biocatalysis , 2nd Edition, Harwood Academic Publishers 1999, pp. 18-53.

[2] K. Faber: Biotransformations in Organic Chemistry , 4th edition, Springer-Verlag Berlin 2000.

[3] Jayasinghe LY, Smallridge AJ, and Trewhella MA: The yeast mediated reduction of ethyl acetoacetate in petroleum ether . In: Tetrahedron Letters . 34, No. 24, 1993, p. 3949. doi : 10.1016 / S0040-4039 (00) 79272-0 .

[Reetz-4] Manfred T. Reetz : Biocatalysis in Organic Chemistry and Biotechnology: Past, Present, and Future , J. Am. Chem. Soc. 135 (2013) pp. 12480-12496.