Biokatalytische Totalsynthese von Ikarugamycin

Biocatalysis: Enzymatic Synthesis for Industrial Applications

Biocatalysis has found numerous applications in various fields as an alternative to chemical catalysis. The use of enzymes in organic synthesis, especially to make chiral compounds for pharmaceuticals as well for the flavors and fragrance industry, are the most prominent examples. In addition, biocatalysts are used on a large scale to make specialty and even bulk chemicals. This review intends to give illustrative examples in this field with a special focus on scalable chemical production using enzymes. It also discusses the opportunities and limitations of enzymatic syntheses using distinct examples and provides an outlook on emerging enzyme classes.

Enzyme alchemy: cell-free synthetic biochemistry for natural products

Cell-free synthetic biochemistry aims to engineer chemical biology by exploiting biosynthetic dexterity outside of the constraints of a living cell. One particular use is for making natural products, where cell-free systems have initially demonstrated feasibility in the biosynthesis of a range of complex natural products classes. This has shown key advantages over total synthesis, such as increased yield, enhanced regioselectivity, use of reduced temperatures and less reaction steps. Uniquely, cell-free synthetic biochemistry represents a new area that seeks to advance upon these efforts and is particularly useful for defining novel synthetic pathways to replace natural routes and optimising the production of complex natural product targets from low-cost precursors. Key challenges and opportunities will include finding solutions to scaled-up cell-free biosynthesis, as well as the targeting of high value and toxic natural products that remain challenging to make either through whole-cell biotransformation platforms or total synthesis routes. Although underexplored, cell-free synthetic biochemistry could also be used to develop 'non-natural' natural products or so-called xenobiotics for novel antibiotics and drugs, which can be difficult to engineer directly within a living cell.

Biosynthesis of the Polycyclic System in the Antifungal HSAF and Analogues from Lysobacter enzymogenes

The biocontrol agent Lysobacter enzymogenes produces polycyclic tetramate macrolactams (PoTeMs), including the antifungal HSAF. To elucidate the biosynthesis of the cyclic systems, we identified eleven HSAF precursors/analogues with zero, one, two, or three rings through heterologous expression of the HSAF gene cluster. A series of combinatorial gene expression and deletion experiments showed that OX3 is the "gatekeeper" responsible for the formation of the first 5-membered ring from lysobacterene A, OX1 and OX2 are responsible for formation of the second ring but with different selectivity, and OX4 is responsible for formation of the 6-membered ring. In vitro experiments showed that OX4 is an NADPH-dependent enzyme that catalyzes the reductive cyclization of 3-dehydroxy alteramide C to form 3-dehydroxy HSAF. Thus, the multiplicity of OX genes is the basis for the structural diversity of the HSAF family, which is the only characterized PoTeM cluster that involves four redox enzymes in the formation of the cyclic system.