Fungal peroxygenases represent an exciting new enzyme class for stereo-selective hydroxylation reactions. They are capable of the oxyfunctionalisation of a large, diverse scope of substrates including alkanes and steroids as well as the heteroatoms sulfur and nitrogen. The outstanding activities and stabilities as well as their reliance on hydrogen peroxide as co-substrate renders it a highly interesting biocatalyst.

In the last decade thiotaurine, 2-aminoethane thiosulfonate, has been investigated as an inflammatory modulating agent as a result of its ability to release hydrogen sulfide (H2S) known to play regulatory roles in inflammation. Thiotaurine can be included in the “taurine family” due to structural similarity to taurine and hypotaurine, and is characterized by the presence of a sulfane sulfur moiety. Thiotaurine can be produced by different pathways, such as the spontaneous transsulfuration between thiocysteine – a persulfide analogue of cysteine – and hypotaurine as well as in vivo from cystine. Moreover, the enzymatic oxidation of cysteamine to hypotaurine and thiotaurine in the presence of inorganic sulfur can occur in animal tissues and last but not least thiotaurine can be generated by the transfer of sulfur from mercaptopyruvate to hypotaurine catalyzed by a sulfurtransferase. Thiotaurine is an effective antioxidant agent as demonstrated by its ability to counteract the damage caused by pro-oxidants in the rat. Recently, we observed the influence of thiotaurine on human neutrophils functional responses. In particular, thiotaurine has been found to prevent human neutrophil spontaneous apoptosis suggesting an alternative or additional role to its antioxidant activity. It is likely that the sulfane sulfur of thiotaurine may modulate neutrophil activation via persulfidation of target proteins. In conclusion, thiotaurine can represent a biologically relevant sulfur donor acting as a biological intermediate in the transport, storage and release of sulfide.

The screening effort of large protein variant libraries renders the probability of coincidental discovering a new enzyme with non-natural activity to almost zero - the so-called numbers problem. Insights into the origin of life, evolution and enzymatic promiscuity, combined with the inspiration of methods from organic chemistry, offer solutions for this problem. With the newly discovered enzymes synthetic micro production units shall be established in a Leibniz Research Cluster where engineering and biotechnology are combined.

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Late stage enzymatic prenylation and methylation are means to diversify (natural) compounds and to specify their functions. In eukaryotes and microbes, these steps are performed by large enzyme families, the prenyl and methyl transferases, which modify various types of small molecules, like isoprenoids, phenolics or alkaloids, but also DNA and proteins. We investigate the theoretical basis of these processes and possible commercial applications in synthetic chemistry.

Multi-component reactions of building blocks with more than one MCR-reactive group will give rise to oligomeric MCR products. The proper choice of at least two bifunctional building blocks will give either a polymeric or a cyclic product. Apart from polymerization, repetitive or consecutive Ugi reactions have been used to produce linear MCR-heterooligomers with such building blocks.

In Arabidopsis, deactivation of cyclin-dependent kinases via phosphorylation has no function in cell proliferation, growth, and stress response. In other eukaryotes, however, this is mandatorily required for maintaining genomic integrity.

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Conformational analysis by NMR spectroscopy and molecular modeling revealed a left-handed PPII helix-like structure for Trp2-Tat(1–9) (cis and trans) and an even more flexible structure for TXA2-R(1–9).PPII helices form a well-defined structural class comparable with the other structures defined in proteins and are characterized by exposed, mobile structures with 4–8 residues, mostly found on the protein surface. Polyproline II helices are mainly identified by their torsion angles of φ∼−75° and Ψ∼145−. They do not form regular interchain hydrogen bonds, but are hydrogen bonded with water molecules. PPII helices have a strong preference for the amino acid proline, although it is not necessarily present. These features were also reported for the parent peptide Tat(1–9)4 as well as for the well known DP IV substrates neuropeptide Y and pancreatic polypeptide5 suggesting that PPII-like helical structures represent a favored structural class for the interaction with DP IV.Thus, the considerable enhancement of the inhibition capacity of both Trp2-Tat(1–9) and TXA2-R(1–9) compared to the moderate inhibitor Tat(1–9)2, Ki=2.68±0.01 10−4 M, can only be due to tryptophan in the second position suggesting that its side chain is favored to exhibit attractive hydrophobic interactions with DP IV compared with aspartic acid.On the other hand, we could show recently that Tat(1–9) and its analogues as well as TXA2-R(1–9) inhibit DP IV according to different inhibition mechanisms (Lorey et al., manuscript submitted). One possible explanation for these findings might be enzyme-ligand interactions relying on multiple weak binding sites as described for PPII helices5 rather than specific lock and key binding. Certainly, only an X-ray structure of DP IV would help to understand the interaction of DP IV with inhibitors.

Our results indicate that the substrate properties of peptides are encoded by their own structure. That means, that substrate characteristics depend not only on the primary structure around the catalytic site rather C-terminal located secondary interactions strongly influence the binding and catalysis of the substrates. Such interaction sites seem to force the ligand in a proper orientation to the active site of DP IV. As result of these relations the hydrolysis of peptides with non-proline and non-alanine residues in P1-position (Ser, Val, Gly) becomes possible in longer peptides.Such specific secondary interactions opens the opportunity for development of new inhibitors.