For a long time, the living cell has been considered to be a perfect chemical factory, whose organizational principles can inspire every organic chemist and chemical engineer. The effectiveness, with which nutrients are converted into complex chemical building blocks required for the cell metabolism, is still a distant goal for any man-made chemical factory. Metabolic pathways, consisting of enzymatic sequential and coupled reactions, lie at the core of any living system and have been optimized by evolution over billions of years to create the phenomenon of life as we know it. In the field of applied biocatalysis, chemists are constantly trying to recognize the principles responsible for the efficiency of cell metabolism and to exploit them in organic synthesis. There are three biological principles whose implementation may be regarded as important milestones in this field and which can be used for the classification of existing biotransformations. One of these principles is that a single reaction step of a given metabolic pathway proceeds in a very specific manner due to the intrinsically high chemo-, regio- and stereoselectivity of the enzyme catalyzing this step. This principle is the soul of applied biocatalysis and has already been widely exploited in the chemical industry for decades in the production of chemicals by enzymatic processes. Biotransformations solely based on this principle, i.e., “single-reaction–singleenzyme” systems, may be classified as first-generation enzymatic processes, which historically were the first to be applied in the chemical industry and till now remain the most abundant among industrial biotransformations.
The article is published online in Beilstein Journal of Organic Chemistry and is free to access.