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The enzyme 4-oxalocrotonate tautomerase (4-OT) promiscuously catalyzes the Michael-type addition of acetaldehyde to β-nitrostyrene derivatives to yield chiral γ-nitroaldehydes, which are important precursors for pharmaceutically active γ-aminobutyric acids. In this study, we investigated the effect of different substituents at the aromatic ring of the Michael acceptor on the catalytic efficiency and stereoselectivity of the 4-OT-catalyzed acetaldehyde addition reactions. Highly enantioenriched ( R)- and ( S)-γ-nitroaldehydes and 4-substituted chroman-2-ol could be obtained in good to excellent yields by applying different substituents at appropriate positions of the aromatic substrate. Stereochemical control of these enzymatic Michael-type additions by 'substrate engineering' allowed the enantioselective synthesis of valuable γ-aminobutyric acid precursors. In addition, the results suggest a novel enzymatic synthesis route towards precursors for chromans and derivatives, which are valuable scaffolds for preparing biologically active natural products. [ABSTRACT FROM AUTHOR]

Call me Michaelase: The enzyme 4‐oxalocrotonate tautomerase (4‐OT) promiscuously catalyzes the Michael‐type addition of acetaldehyde to a collection of aromatic and aliphatic nitroolefins with high stereoselectivity producing precursors of γ‐aminobutyric acid (GABA) analogues (see scheme). [ABSTRACT FROM AUTHOR]

The role of Kallikrein 10 gene (KLK10) in non-small cell lung cancer (NSCLC) remains largely unknown. We determined the frequency and functional significance of KLK10 hypermethylation in NSCLC. The mRNA expression and methylation status of KLK10 in 78 pairs NSCLC specimens was explored. The biological effects of KLK10 were analyzed by transfection. The results showed that, KLK10 was significantly downregulated in NSCLC (57.7%, 45/78) as compared to non-cancer samples ( P = 0.010). CpG island hypermethylation of KLK10 was detected in 46.2% (36/78) NSCLC tissues and was closely correlated with loss of transcript ( P < 0.001). KLK10 methylation was associated with advanced stage ( P = 0.013) and lymph metastasis ( P = 0.015). Furthermore, demethylation treatment restored the expression of KLK10 in two lung adencarcinoma cell lines (A549, SPC-A1). Forced expression of KLK10 in A549 and SPC-A1 remarkably suppressed cells proliferation, migration in vitro and oncogenicity in vivo. Additionally, methylated KLK10 was detected in 38.7% (30/78) of plasma samples from cancer patients but rare in cancer-free controls ( P < 0.001). In conclusion, KLK10 acts as a functional tumor suppressor gene in NSCLC, epigenetic inactivation of KLK10 is a common event contributing to NSCLC pathogenesis and may be used as a potential biomarker. ( Cancer Sci 2010; 101: 934–940) [ABSTRACT FROM AUTHOR]

The article presents chemical equations for article "Biocatalytic Michael-Type Additions of Acetaldehyde to Nitroolefins with the Proline- Based Enzyme 4-Oxalocrotonate Tautomerase Yielding Enantioenriched γ-Nitroaldehydes" by Y. Miao and others, in "Chemistry: A European Journal" in 2013.