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661.
The chemoenzymatic epoxidation of a terpene alcohol, citronellol, is reported. Some experimental conditions, such as the use of lipases from different sources, oxidizing agents (H2O2 or urea–hydrogen peroxide, UHP), reaction time, acyl donor type (C6–C16), temperature (15–40 °C) and the influence of organic media, were evaluated. In most cases, citronellol oxide 2 or the ester citronellol oxide 3 were obtained. Depending on the reaction conditions, high yields of products 2 or 3 were obtained (>99%). CAL-B was the most effective catalyst in this reaction. For epoxide 2, the highest yields of 80% and 77% were obtained at 20 °C and 25 °C, respectively, using UHP as an oxidizing agent and octanoic acid as an acyl donor. The organic medium appears to be one of the most important parameters in the reaction. Using chloroform or dichloromethane, product 2 was obtained at a >99% yield after 24 h. When different mixtures consisting of varied organic solvents and an imidazolium-based ionic liquid (IL) were used, the results were dependent on both the solvent and IL counter-ion (18–75%). 相似文献
662.
Charles R. Hipkin Jaqueline A. Hermann-Smith Philip J. Syrett 《Biochimica et Biophysica Acta (BBA)/General Subjects》1985,838(2):191-196
The appearance of nitrate reductase activity in derepressed cultures of the Nit A mutant of Chlamydomonas reinhardtii required concomitant photosynthetic CO2 fixation and was inhibited when protein turnover was prevented. Provided leupeptin was included in the extraction buffer, a single species of nitrate reductase (molecular mass, m = 390 kDa) was extracted from Nit A cultures incubated in nitrate medium for 4 h. Cultures of the mutant incubated in nitrate-free medium contained a number of nitrate reductase species (m = 52–500 kDa). This evidence suggests that nitrate plays a role in the stabilisation of the structure of the mutant nitrate reductase. Only one species of nitrate reductase (m = 188 kDa) was extracted from wild type cultures grown with nitrate. 相似文献
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Gauthier Mariana Fraga de Andrade Andressa Alves Fisch Joana Feistauer Vanessa Morás Ana Moira Reinhardt Luiza Steffens de Moura Ana Carolina Moura Dinara Jaqueline de Almeida Silvana Guedes Renata Padilha Giovenardi Márcia 《Journal of physiology and biochemistry》2022,78(1):271-282
Journal of Physiology and Biochemistry - Maternal diet is key to the progeny’s health since it may impact on the offspring’s adult life. In this study, mice dams received standard... 相似文献
665.
Antonio G. Gonz lez Lucia S. Andr s Javier G. Luis Ivan Brito Matias L. Rodrí guez 《Phytochemistry》1991,30(12):4067-4070
Two new aromatic diterpenes have been obtained from the aerial part of Salvia mellifera and their structures identified, on the basis of spectral data and chemical correlations, as 11,12,20-trihydroxy-abieta-8,11,13-triene and 11,12,16-trihydroxy- abieta-8,11,13-trien-20-al. The known diterpenes, carnosic acid, carnosol, rosmanol, isorosmanol, galdosol, rosmadial, 9 (10 → 20)-abeo-abieta-8,11,13-triene-10β,11,12-triol (demethylsalvicanol)and salvicanol were also isolated from the same source. The absolute configuration of salvicanol was established by X-ray diffraction analysis of its 11-p-bromobenzoate derivative. 相似文献
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