The art to make 'impossible' reactions work by using the most powerful catalysts on earth – enzymes – is known as biocatalysis. There is one driving force behind our projects, i.e. cutting tedious asymmetric syntheses short.
During the 1980s we have mainly been using industrially produced enzymes (such as lipases, esterases and proteases), which offers the advantage that the chiral catalyst comes in a nice parcel by mail. On the other hand, other chemists do the same. Confronted by some tough competition we went into Nature's supermarket (we usually prefer the NCIMB-, or IFO- and DSM-branch) in search for novel enzymes. Other people breed dogs, we subsequently started to grow our own 'pet' biocatalysts. This, of course, proceeded numerous heart-felt warnings by the microbiologists next door, who expressed their unshakeable belief that organic chemists are too stupid to grow bugs.
Fortunately, the bugs did not share this prejudice. They grew well, because we fed them tasty goodies. After all, even microorganisms do not bite the hand that feeds them. Meanwhile our culture collection (where FCC stands for 'Fab-Crew-Collection') contains some 300 microbial strains encompassing bacteria, lower and higher fungi and, most recently, also a selected set of extremophiles.

For an overview on biotransformations and a textbook see:

• K. Faber, W. Kroutil, Curr. Opinion Chem. Biol. 2005, 9, 181.
• K. Faber, Pure Appl. Chem. 1997, 69, 1613.
• K. Faber, Biotransformations in Organic Chemistry, 6th revised edn., Springer, Heidelberg, 2011;
  423 pages, 29 tables, 286 schemes, 38 figures, ~2600 references

Green redox chemistry employing alcohol dehydrogenases

A large number of redox-reactions in organic chemistry are still based on (heavy) metals, many of which are (i) expensive, (ii) toxic, (iii) environmentally inacceptable (in particular when required in molar amounts) and (iv) difficult to remove from the product(s). As a consequence, any metal-independent method to perform redox-reactions would present a viable alternative. Alcohol dehydrogenases (ADHs) have long been used for the bioreduction of carbonyl compounds and (to a lesser extent) for the biooxidation of alcohols. read more...

Deracemization techniques

Although the biocatalytic literature is full of kinetic resolutions using hydrolytic enzymes such as lipases, esterases and proteases, there are several drawbacks associated with those reactions: The reaction has to be terminated at 50% conversion, yielding a 1:1-mixture of formed product and remaining substrate, which have to be separated (usually by boring flash chromatography). As the maximum theoretical yield of substrate and product is 50% each and there is only need for one stereoisomer, the other has to be discarded. read more...

Alkyl Sulfatases

In order to keep things simple, we envisaged to transform both enantiomers of a racemate via independent and stereochemically matching pathways directly into a single stereoisomeric product. In order to meet this goal, both enantiomers have to be processed with retention and inversion of configuration, respectively. As a consequence, the catalyst(s) required do not only have to be enantio-, but also stereo-selective at the same time – a rather difficult task, but a piece of cake for enzymes! The alkyl sulfatases which can perform this task are being investigated in this context. read more...

Biocatalytic Cascade reactions

Reactions proceeding through more than a single step in a concurrent fashion are generally denoted as domino- or cascade-reactions. Despite the fact that they may proceed via a highly reactive, unstable intermediate (which often eludes isolation), the final product often can be isolated in good yields. This is due to the fact that decomposition of the intermediate is largely retarded since it is transformed in the same instant as it appears and is never present in measurable concentrations. By making use of the stereoselectivity of enzymes, cascade-reactions can be rendered in an asymmetric fashion, if the first reaction step within the cascade is 'triggered' by a biocatalyst. read more...

Alkene cleavage

The development of "green" chemical oxidation processes belongs to the burning hot topics in organic chemistry. Ozonisation of C=C double bonds giving access to carbonyl compounds (under reductive conditions) is one of the most used oxidation methods for C=C cleavage. However, safety hazards and the need for special equipment as well as reducing reagents in molar amounts complicate this reaction. Other C=C cleaving protocols require stoichiometric amounts of oxidants such as metal-based reagents (e. g. NaIO4, Cr-, Ru-salts). By serendipity we identified a simple biocatalytic alternative employing a cell extract from Trametes sp. in buffer and consumption of molecular oxygen without production of waste. read more...

Asymmetric Conjugate Reduction of Activated C=C Bonds

The asymmetric bioreduction of alkenes bearing an electron-withdrawing group leads to the creation of up to two chiral carbon centers. The enzymes responsible for this useful transformation are flavoproteins from the 'old-yellow-enzyme family' (often denoted as enoate- or ene-reductases) which ultimately derive their reduction equivalents from of NAD(P)H. read more...

Asymmetric amination employing ω-transaminases

ω-Transaminases employ pyridoxal-5´-phosphate (PLP) as cofactor to transfer formally ammonia and electrons from an amino donor to a ketone acceptor. In contrast to a-amino acid aminotransferases, ω-transaminases possess the capability to convert also substrates lacking an a-carboxylic moiety, making them therefore very attractive for organic synthesis. The advantage of using ω-transaminases read more...

Computer modeling of biocatalytic reactions

Many biocatalytic reactions are proceeding via more than one step, and the kinetics of these processes are usually a nightmare for the organic chemist – just imagine that the product from step 1 constitutes the substrate for step 2. In order to facilitate the understanding of complex kinetics, we have developed several computer programs which have a nice and user-friendly surface while all the dry and boring math is hidden behind the screen. All programs are available free of charge from our ftp-server at ftp://borgc185.kfunigraz.ac.at for both Windows and MacOS. read more...

Enzymatic carboxylation

In order to alleviate the predominant dependence of the chemical industry from petroleum-based platform intermediates, the development of CO2-fixation reactions represents a major challenge in synthetic organic chemistry, which would allow to convert a problematic waste gas into a useful carbon source for the production of chemicals. Since Nature is fixing CO2 on large scale, we are trying to copy some tricks for the synthesis of carboxylic acids. read more...

Cyclases in biosynthesis

The biosynthesis of complex natural products is not carried out in a stepwise fashion, but through enzyme-initiated cascade processes. Analysis of the underlying principles revealed that cyclic terpenoids are generally obtained by electrophilic cascades (via intermediate carbenium ions), whereas cyclic polyethers are formed by nucleophilic cascade reactions from (poly)epoxide precursors. These mechanistically complementary pathways follow common principles via read more...

C-C bond hydrolases in organic synthesis

Although hydrolases cleaving carbon-heteroatom bonds have been successfully used as biocatalysts in asymmetric reactions for a long time, the potential applications of C-C-bond hydrolases in biotransformations have not been widely investigated. C-C-bond hydrolases are enzymes capable of catalysing the hydrolytic cleavage of selected ketonic substances, such as ß-diketones (retro-Claisen reaction). read more...