RESUMO
Direct, NAD(P)H-independent regeneration of Old Yellow Enzymes represents an interesting approach for simplified reaction schemes for the stereoselective reduction of conjugated C=C-double bonds. Simply by illuminating the reaction mixtures with blue light in the presence of sacrificial electron donors enables to circumvent the costly and unstable nicotinamide cofactors and a corresponding regeneration system. In the present study, we characterise the parameters determining the efficiency of this approach and outline the current limitations. Particularly, the photolability of the flavin photocatalyst and the (flavin-containing) biocatalyst represent the major limitation en route to preparative application.
Assuntos
Mononucleotídeo de Flavina/química , NADPH Desidrogenase/química , Bacillus subtilis/enzimologia , Catálise , Cicloexanonas/química , Escherichia coli/genética , Mononucleotídeo de Flavina/efeitos da radiação , NADPH Desidrogenase/genética , NADPH Desidrogenase/efeitos da radiação , Oxirredução , Fotoquímica , Proteínas Recombinantes/química , Proteínas Recombinantes/efeitos da radiaçãoRESUMO
The encapsulation of chloroperoxidase from Caldariomyces fumago (CPO) in block copolymer polymersomes is reported. Fluorescence and electron microscopy show that when the encapsulating conditions favour self-assembly of the block copolymer, the enzyme is incorporated with concentrations that are 50 times higher than the enzyme concentration before encapsulation. The oxidation of two substrates by the encapsulated enzyme was studied: i) pyrogallol, a common substrate used to assay CPO enzymatic activity and ii) thioanisole, of which the product, (R)-methyl phenyl sulfoxide, is an important pharmaceutical intermediate. The CPO-loaded polymersomes showed distinct reactivity towards these substrates. While the oxidation of pyrogallol was limited by diffusion of the substrate into the polymersome, the rate-limiting step for the oxidation of thioansiole was the turnover by the enzyme.
Assuntos
Ascomicetos/enzimologia , Biocatálise , Cloreto Peroxidase/metabolismo , Nanoestruturas/microbiologia , Polímeros/metabolismo , Filtração , Cinética , Microscopia Confocal , Modelos Químicos , Oxirredução , Pirogalol/química , Pirogalol/metabolismo , Espectrofotometria Ultravioleta , Sulfetos/química , Sulfetos/metabolismo , Enxofre/metabolismo , Fatores de TempoRESUMO
Confinement of nanometallic Pd within the core of a hyperthermophilic ferritin cage (from Pyrococcus furiosus) is reported. The resulting nanostructured hybrid catalysts can be used for highly specific aerobic oxidation of alcohols in water.