ABSTRACT
Fatty acid synthase (FAS) catalyses the reaction between acetyl-CoA and malonyl-CoA to produce fatty acids. It is one of the most important enzyme in lipid biosynthesis. FAS of the oleaginous yeast Rhodosporidium toruloides has two acyl carrier protein (ACP) domains and a distinct subunit composition compared with FASs of other species. As ACP is a protein cofactor crucial for fatty acid chain elongation, more ACPs in the FAS may facilitate the reaction. To study the biochemical and structural properties of this novel FAS from R. toruloides, plasmids were constructed and transformed into Escherichia coli BL21 (DE3). The strain ZWE06 harboring plasmids pET22b-FAS1 and pET24b-FAS2 could co-overexpress the two subunits. The recombinant FAS was purified by sequentially using ammonium sulphate precipitation, sucrose density gradient centrifugation and anion exchange chromatography. The specific activity of the recombinant FAS was 548 mU/mg. The purified complex would be used to study enzyme kinetics and protein structure of FAS, and heterogeneous expression and purification will facilitate revealing the mechanism of this novel FAS with double ACPs.
Subject(s)
Acyl Carrier Protein , Basidiomycota , Chromatography , Escherichia coli , Metabolism , Fatty Acid Synthases , Genetics , Fatty Acids , Plasmids , Recombinant Proteins , GeneticsABSTRACT
Cholesterol oxides are atherogenic and can affect the activity of diverse important enzymes for the lipidic metabolism. The effect of 7β-hydroxycholesterol, 7-ketocholesterol, 25-hydroxycholesterol, cholestan-3β,5α,6β-triol,5,6β-epoxycholesterol, 5,6α-epoxycholesterol and 7α-hydroxycholesterol on esterification of cholesterol by lecithin:cholesterol acyl transferase (LCAT, EC 2.3.1.43) and the transfer of esters of cholesterol oxides from high density lipoprotein (HDL) to low density lipoproteins (LDL) and very low density lipoproteins (VLDL) by cholesteryl ester transfer protein (CETP) was investigated. HDL enriched with increasing concentrations of cholesterol oxides was incubated with fresh plasma as source of LCAT. Cholesterol and cholesterol oxides esterification was followed by measuring the consumption of respective free sterol and oxysterols. Measurements of cholesterol and cholesterol oxides were done by gas-chromatography. 14C-cholesterol oxides were incorporated into HDL2 and HDL3 subfractions and then incubated with fresh plasma containing LCAT and CETP. The transfer of cholesterol oxide esters was followed by measuring the 14C-cholesterol oxide-derived esters transferred to LDL and VLDL. All the cholesterol oxides studied were esterified by LCAT after incorporation into HDL particles, competing with cholesterol by LCAT. Cholesterol esterification by LCAT was inversely related to the cholesterol oxide concentration. The esterification of 14C-cholesterol oxides was higher in HDL3 and the transfer of the derived esters was greater from HDL2 to LDL and VLDL. The results suggest that cholesterol esterification by LCAT is inhibited in cholesterol oxide-enriched HDL particles. Moreover, the cholesterol oxides-derived esters are efficiently transferred to LDL and VLDL. Therefore, we suggest that cholesterol oxides may exert part of their atherogenic effect by inhibiting cholesterol esterification...
Os óxidos de colesterol são aterogênicos e podem afetar a atividade de diversas enzimas importantes para o metabolismo lipídico. Este estudo investigou o efeito dos óxidos 7β-hidroxicolesterol, 7-cetocolesterol, 25-hidroxicolesterol, colestan-3β,5α,6β-triol, 5,6β-epoxicolesterol, 5,6α-epoxicolesterol e 7α-hidroxicolesterol na esterificação do colesterol por ação da lecitina colesterol aciltransferase (LCAT, EC 2.3.1.43) e a posterior transferência dos óxidos esterificados da lipoproteína de alta densidade (HDL) para as lipoproteínas de baixa densidade (LDL) e muito baixa densidade (VLDL) mediada pela proteína de transporte de éster de colesterol (CETP). Para atingir os objetivos, HDL enriquecida com concentrações crescentes de óxidos de colesterol foi incubada com plasma fresco pobre em lipoproteínas, como fonte de LCAT; posteriormente a esterificação do colesterol e dos óxidos de colesterol foi medida pelo consumo do colesterol livre e dos óxidos livres presentes na HDL. As determinações de colesterol e dos óxidos de colesterol foram realizadas por cromatografia gasosa. 14C-óxidos de colesterol foram incorporados nas subfrações HDL2 e HDL3 e posteriormente incubados com plasma fresco, contendo LCAT e CETP. A transferência dos ésteres de óxidos de colesterol foi medida e quantificada pela presença desses ésteres na LDL e VLDL. Todos os óxidos de colesterol estudados foram esterificados pela LCAT após incorporação nas partículas de HDL e competiram com a esterificação do colesterol nativo. A esterificação do colesterol pela LCAT foi inversamente relacionada à concentração de óxidos de colesterol. A esterificação dos óxidos de colesterol foi maior na HDL3 e a transferência desses ésteres foi maior a partir da HDL2 para a LDL e VLDL. Estes resultados indicam que a esterificação do colesterol pela LCAT é inibida nas partículas de HDL enriquecidas com óxidos de colesterol e que os ésteres de óxidos de colesterol...
Subject(s)
Humans , Male , Female , Adult , Acyl Carrier Protein , Cholesterol , Lecithins/biosynthesis , Oxides , Transferases , Lipoproteins, HDL , Sterol O-AcyltransferaseABSTRACT
La utilización de caldos microbiales es un ejemplo de tecnologías posibles de usar, ofreciendo grandes ventajas que difícilmente pueden lograrse con los fertilizantes inorgánicos. Los biofertilizantes, o caldos microbiales, son cultivos de microorganismos, elaborados con base en estiércol de origen animal, disueltos en agua y enriquecidos con leches, sueros, fermentación, anaeróbico o aeróbico durante varios días. Los abonos orgánicos (biofertilizantes) son recomendados en suelos degradados ya que facilitan la disponibilidad de nutrientes. Se realizó la evaluación del efecto de la aplicación de tres caldos microbiales preparados con base en avestruzaza, humus y bovinaza en la producción y calidad nutricional del forraje del pasto India guinea (Panicum máximum), comparado con los efectos del manejo tradicional (sin fertilización) y convencional (fertilización química), en la finca la primavera del municipio de Nilo (Cund), y se compararon sus costos. Los resultados mostraron mejoría en el porcentaje de proteína obtenida de forrajes trabajados con urea. Respecto a la producción de forraje verde, los mejores resultados se obtuvieron con avestruzaza, bovinaza y urea respectivamente, aunque no hubo diferencias significativas entre ellos. Loa costos de fertilización con biopreparados son inferiores en menos del 50 por ciento y los rendimientos en producción y calidad del forraje son mayores comparados con la fertilización convencional...