4 research outputs found

    EL SILENCIO EN EL MONSTRUO DEL MANZANARES

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    Este trabajo estudia la función del silencio en la novela El monstruo del Manzanares, novela corta incluida en la colección La mojiganga del gusto (1641) de Andrés Sanz del Castillo. Esta novela posee constantes alusiones al silencio, las cuales, sumadas a la ausencia de diálogos que reproduzcan las voces de los personajes, nos llevan a considerar, más allá todavía, que el silencio configura un tema en sí mismo dentro de El monstruo de Manzanares y determina notoriamente el sentido final de la novela

    Engineering of Acid-Resistant d‑Allulose 3‑Epimerase for Functional Juice Production

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    d-Allulose, a rare sugar and functional sweetener, can be biosynthesized by d-allulose 3-isomerase (DAE). However, most of the reported DAEs exhibit poor resistance under acidic conditions, which severely limited their application. Here, surface charge engineering and random mutagenesis were used to construct a mutant library of CcDAE from Clostridium cellulolyticum H10, combined with high-throughput screening to identify mutants with high activity and resistance under acidic conditions. The mutant M3 (I114R/K123E/H209R) exhibited high activity (3.36-fold of wild-type) and acid resistance (10.6-fold of wild-type) at pH 4.5. The structure–function relationship was further analyzed by molecular dynamics (MD) simulations, which indicated that M3 had a higher number of hydrogen bonds and negative surface charges than the wild type. A multienzyme cascade system including M3 was used to convert high-calorie sugars in acidic juices, and functional juices containing 7.8–15.4 g/L d-allulose were obtained. Our study broadens the manufacture of functional foods containing d-allulose

    Computation-Aided Phylogeny-Oriented Engineering of β‑Xylosidase: Modification of “Blades” to Enhance Stability and Activity for the Bioconversion of Hemicellulose to Produce Xylose

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    Hemicellulose is a highly abundant, ubiquitous, and renewable natural polysaccharide, widely present in agricultural and forestry residues. The enzymatic hydrolysis of hemicellulose has generally been accomplished using β-xylosidases, but concomitantly increasing the stability and activity of these enzymes remains challenging. Here, we rationally engineered a β-xylosidase from Bacillus clausii to enhance its stability by computation-aided design combining ancestral sequence reconstruction and structural analysis. The resulting combinatorial mutant rXYLOM25I/S51L/S79E exhibited highly improved robustness, with a 6.9-fold increase of the half-life at 60 °C, while also exhibiting improved pH stability, catalytic efficiency, and hydrolytic activity. Structural analysis demonstrated that additional interactions among the propeller blades in the catalytic module resulted in a much more compact protein structure and induced the rearrangement of the opposing catalytic pocket to mediate the observed improvement of activity. Our work provides a robust biocatalyst for the hydrolysis of agricultural waste to produce various high-value-added chemicals and biofuels
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