Carbonic anhydrase is a zinc metalloenzyme that catalyzes the hydration of carbon dioxide to bicarbonate. Replacing the active-site zinc with manganese yielded manganese-substituted carbonic anhydrase (CA[Mn]), which shows peroxidase activity with a bicarbonate-dependent mechanism. In the presence of bicarbonate and hydrogen peroxide, (CA[Mn]) catalyzed the efficient oxidation of o-dianisidine ...

The chemo-enzymatic epoxidation of rapeseed methyl ester (RME) in a solvent-free medium was studied using the immobilized Candida antarctica lipase B (Novozym® 435) as catalyst. Hydrogen peroxide (H2O2) was used as the oxygen donor. The enzyme cost is an important factor determining the economics of the process. High enzyme stability and the possibility to recycle the enzyme are therefore highl...

Este trabalho descreve nosso esforço em heterogeneizar catalisadores para epoxidação. Tanto o molibdênio ancorado quanto o engaiolado pelo método de sol-gel mostraram grande seletividade, mas possuem suas atividades fortemente reduzidas. Por outro lado, silicatos de molibdênio foram muito ativos e estáveis até a formação de diols na mistura reacional. Catalisadores heterogeneizados de rênio for...

Treatment of the solvent adduct [MoO2Cl2(THF)2] with either 2 equivalents of N,N-dimethylbenzamide (DMB) or 1 equivalent of N,N'-diethyloxamide (DEO) gave the dioxomolybdenum(vi) complexes [MoO2Cl2(DMB)2] () and [MoO2Cl2(DEO)] (). The molecular structures of and were determined by single-crystal X-ray diffraction. Both complexes present a distorted octahedral geometry and adopt the cis-oxo, tra...

SBA-15 materials were functionalized through a post-synthetic methodology with molybdenum-Schiff bases to provide catalytic activity in epoxidation reactions. Thus, glycidoxypropyl functionalities were first attached to the surface of the mesostructured silica, followed by the reaction of the immobilized oxirane groups with 2-amino propyl pyridine. This reaction allowed the obtaining of (hydrox...

In the past 15 years considerable progress has been made in the field of homogeneous catalyzed epoxidations of unfunctionalized olefins. Epoxidation is an important methodology for preparation of highly functionalized organic compounds; optically active epoxides especially are important intermediates. From many olefins it is now possible to create in only one step optically active epoxides in n...

The biosynthesis of the antifungal agent pimaricin by Streptomyces natalensis has been proposed to involve a cytochrome P450 encoded by the gene pimD. Pimaricin is derived from its immediate precursor de-epoxypimaricin by epoxidation of the C-4-C-5 double bond on the macrolactone ring. We have overproduced PimD with a N-terminal His6 affinity tag in Escherichia coli and purified the enzyme for ...

Changes in actual efficiency of PS II photochemistry, non-photochemical quenching (NPQ), content of xanthophylls and kinetics of de-epoxidation were studied in ABA-fed and non-ABA-fed leaves of rice and cabbage under NaCl stress. Salt stress induced more progressive decrease in actual efficiency of PS II photochemistry (ФPS II), higher reduction state of PS II, and a small significant increase ...

Modification of graphitic carbon nitride (g-C(3)N(4)) photocatalyst with transition metals was achieved with a simple soft-chemical approach using dicyandiamide monomer and metal chloride as precursors, in combination with a thermal-induced polycondensation at 600 °C under nitrogen atmosphere. The resultant organic-inorganic hybrid materials were thoroughly characterized by a variety of techniq...

VO2+ and its complexes with ethylenediamine (en), acetylacetonate (acac), 2, 2’-bipyridine(bpy) ligands, immobilized within nanoreactors of Al-MCM-41 designated as VO2+/Al-MCM-41 or VOL2/Al-MCM-41, were prepared and characterized by X-ray powder diffraction (XRD), FT-IR, BET nitrogen adsorption-desorption and chemical analysis techniques. VO2+/Al-MCM-41 and VOL2/Al-MCM-41 were found to catalyze...