Kinetic Resolution of Homoaldols via Catalytic Asymmetric Transacetalization
摘要:
The highly enantioselective kinetic resolution of homoaldols via a transacetalization reaction has been achieved. A novel phosphoric acid, STRIP, based on a spirocyclic 1,1'-spirobiindane backbone was designed and identified as a superior catalyst for this transformation. Remarkably, both secondary and tertiary homoaldols gave equally excellent results.
NADP+-dependent dehydrogenase activity of carbonyl reductase on glutathionylhydroxynonanal as a new pathway for hydroxynonenal detoxification
摘要:
An NADP(+) -dependent dehydrogenase activity on 3-glutathiony1-4-hydroxynonanal (GSHNE) was purified to electrophoretic homogeneity from a line of human astrocytoma cells (ADF). Proteomic analysis identified this enzymatic activity as associated with carbonyl reductase 1 (EC 1.1.1.184). The enzyme is highly efficient at catalyzing the oxidation of GSHNE (K-M 33 mu M, k(cat) 405 min(-1)), as it is practically inactive toward trans-4-hydroxy-2-nonenal (HNE) and other HNE-adducted thiol-containing amino acid derivatives. Combined mass spectrometry and nuclear magnetic resonance spectroscopy analysis of the reaction products revealed that carbonyl reductase oxidizes the hydroxyl group of GSHNE in its hemiacetal form, with the formation of the corresponding 3-glutathionylnonanoic-delta-lactone. The relevance of this new reaction catalyzed by carbonyl reductase 1 is discussed in terms of HNE detoxification and the recovery of reducing power. (C) 2015 Published by Elsevier Inc.