Pseudomonas sp. VLB120 uses styrene as a sole source of carbon and energy. The first step in this metabolic pathway is catalyzed by an oxygenase (StyA) and a NADH-flavin oxidoreductase (StyB). Both components have been isolated from wild-type Pseudomonas strain VLB120 as well as from recombinant Escherichia coli. StyA from both sources is a dimer, with a subunit size of 47 kDa, and catalyzes the enantioselective epoxidation of CAC double bonds. Styrene is exclusively converted to S-styrene oxide with a specific activity of 2.1 U mg

The compounds CGP7930 [2,6-Di-tert-butyl-4-(3-hydroxy-2,2-dimethyl-propyl)-phenol] and its close analog CGP13501 were identified as positive modulators of gamma-aminobutyric acid(B) (GABA(B)) receptor function. They potentiate GABA-stimulated guanosine 5'-O-(3-[(35)S]thiotriphosphate) (GTP gamma[(35)S]) binding to membranes from a GABA(B(1b/2)) expressing Chinese hamster ovary (CHO) cell line at low micromolar concentrations and are ineffective in the absence of GABA. The structurally related compounds propofol and malonoben are inactive. Similar effects of CGP7930 are seen in a GTP gamma[(35)S] binding assay using a native GABA(B) receptor preparation (rat brain membranes). Receptor selectivity is demonstrated because no modulation of glutamate-induced GTP gamma[(35)S] binding is seen in a CHO cell line expressing the metabotropic glutamate receptor subtype 2. Dose-response curves with GABA in the presence of different fixed concentrations of CGP7930 reveal an increase of both the potency and maximal efficacy of GABA at the GABA(B(1b/2)) heteromer. Radioligand binding studies show that CGP7930 increases the affinity of agonists but acts at a site different from the agonist binding site. Agonist affinity is not modulated by CGP7930 at homomeric GABA(B(1b)) receptors. In addition to GTP gamma[(35)S] binding, we show that CGP7930 also has modulatory effects in cellular assays such as GABA(B) receptor-mediated activation of inwardly rectifying potassium channels in Xenopus laevis oocytes and Ca(2+) signaling in human embryonic kidney 293 cells. Furthermore, we show that CGP7930 enhances the inhibitory effect of L-baclofen on the oscillatory activity of cultured cortical neurons. This first demonstration of positive allosteric modulation at GABA(B) receptors may represent a novel means of therapeutic interference with the GABA-ergic system.

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Cell‐free enzymatic oxidations: Styrene monooxygenase (StyA) was used as a reagent for the gram‐scale preparation of enantiopure epoxides. The catalyst is highly stable in a biphasic system and results in conversions of more than 88 %. R1=H, Cl; R2=R3=H, CH3.

We report the first example of direct electrochemical regeneration of a flavin-dependent monooxygenase for asymmetric epoxidation catalysis. It is shown that electrochemical regeneration of the oxygenase subunit of the multicomponent styrene monooxygenase is sufficient to perform enantiospecific S-epoxidation of various styrene derivatives. Kinetic bottlenecks of the novel electroenzymatic reaction are identified. This work opens up new alternatives for asymmetric oxyfunctionalization catalysis.