Feruloyl, chlorogenate esterases, and tannases are enzymes useful in phenolic modifications of pharmaceutical relevance as protectors against several degenerative human diseases. Therefore, there is a growing interest in discovering new sources of these enzymes. However, traditional methods for their activity measurements are time-consuming and poorly adapted for high-throughput screening. In this study, a successful new microplate high-throughput screening method for the simultaneous quantification of all mentioned activities is demonstrated. This method allows the detection of activities as low as 1.7 mU ml(-1). Furthermore, reaction rates increased proportionally with the amount of enzyme added, and no interferences with the other commercial hydrolases tested were found. The utility of the method was demonstrated after simultaneously screening feruloyl, chlorogenate esterase, and tannase activities in solid state fermentation extracts obtained during the kinetics of production of 20 fungal strains. Among these, seven strains were positive for at least one of the esterase activities tested. This result shows the potential for the rapid routine screening assays for multiple samples of moderate low to high enzymatic levels.

The effect of urea and guanidine hydrochloride (GdmCl) on the activity of heart lactate dehydrogenase, glycerol-3-phosphate dehydrogenase, hexokinase, inorganic pyrophosphatase, and glyceraldehyde-3-phosphate dehydrogenasc was studied in low-water systems. Most of the experiments were made in a system formed with toluene, phospholipids, Triton X-100, and water in a range that varied over 1.0-6.5% (by vol.) [Garza-Ramos, G., Darszon, A., Tuena de Gomez-Puyou, M. & GomezPuyou, A. (1990) Biochemistry 29, 751 -7571. In such conditions at saturating substrate conccntrations, the activity of the enzymes was more than 10 times lower than in all-water media. However the activity of the first four aforementioned enzymes was increased between 4 and 20 times by the denaturants. The most marked activating effect was found with lactate dehydrogenase; with 3.8% (by vol.) water maximal activation was observed with 1.5 M GdmCl (about 20-fold); 4 M urea activated, but to a lower extent. Activation by guanidine thiocyanate was lower than with GdmCI. The activating and inactivating effects of GdmCl on lactate dehydrogenase depended on the amount of water; as the amount of water was increased from 2.0% to 6.0% (by vol.), activation and inactivation took place with progressively lower GdmCl concentrations. When activity was measured as a function of the volume of 1.5 M GdmCl solution, a bell-shaped activation curve was observed. In a low-water system formed with n-octane, hexanol, cetyltrimethylammonium bromide and 3.0% water, a similar activation of lactate dehydrogenase by GdmCl and urea was observed. The water solubility diagrams were modified by GdmCl and urea, and this could reflect on cnzyme activity. However, from a comparison of denaturant concentrations on the activity of the enzymes studied, it would scem that, independently of their effect on the characteristics of the low-water systems, denaturants bring about activation through their known mechanism of action on the protein. It is suggested that the effect of denaturants is due to the release of constraints in enzyme catalysis imposed by a low-water environment.

The effect of urea and guanidine hydrochloride (GdmC1) on the activity of lactate dehydrogenases from heart and muscle was studied in standard water mixtures and in reverse micelles formed with n-octane, hexanol, cetyltrimethykdmmonium bromide and water in a concentration that ranged over 2.5 -6.0% (by vol.). In all water mixtures GdmCl (0.15-0.75 M) and urea (0.5-3.0 M) inhibited the activity of the enzymes at non-saturating pyruvate concentrations. At concentrations of pyruvate that proved inhibitory for enzyme activity due to the formation of a ternary enzyme-NAD-pyruvate complex, GdmCl and urea increased the activity of the enzymes. This increase correlated with a decreasc of the ternary complex, as evidenced by its absorbance at 320-325 nm. In the low-water system it was found that: (a) at all concentrations of pyruvate tested (0.74 -30 mM), GdmCl enhanced the activity of the heart enzyme to a similar extent; (b) in the muscle enzyme, GdmCl inhibited or increased the activity through a proccss that depended on the concentration of pyruvate and GdmCl; (c) under optimal conditions, the activation by GdmCl was about two times lower in the muscle than in the heart enzyme, although in all-water media the activity of the muscle enzyme was twice as high. The expression of lactate dehydrogenase activity in the low-water system was higher with the heart than with the muscle enzyme compared to their activities in all-water media (about 260 and 600 pmol min-I mg-' in the heart and muscle enzymes respectively). Apparently for catalysis, the water requirement in the heart enzyme is lower than in the muscle enzyme. It is likely that the different response of the two enzymes to solvent is due to their distinct structural features.For a long time it has been known that guanidine salts and urea disrupt the three-dimensional structure of proteins [l]. However, there are reports that indicate that the activity of an important number of enzymes is diminished [2-51 or enhanced 16-121 by denaturants at concentrations that do not produce gross changes of protein structure. The mechanisms that account for these effects are not known with certainty, but it has been suggested that they take place through modifications of the catalytic site, or to an increase in the flexibility of the enzyme. In the preceding paper [13], it was shown that, in reverse micelle systems with a low water content, the activity of four out of five enzymes tested could be increased severalfold by denaturants. Here the activities of heart and muscle lactate dehydrogenases were studied in allaqueous media and in a low-water system with and without denaturants. The studies were an attempt to ascertain if indeed, and how, thc structural differences of the isoenzymes affect their functional response to solvent modifications. The experiments werc made in all-water mixtures and in reverse micelles formed with cetyltrimethylammonium bromide, hexanol, and n-octane [14, 151. Lactate dehydrogenase has the advantage that it is one of the most thoroughly studied enzymes....

La presente revisión sistemática de literatura (SLR) pretende abordar e identificar la producción académica en la temática de educación en valores para la Educación Superior del siglo XXI, donde se verifica la necesidad de basar la educación en valores en el contexto actual. Esta investigación, toma como punto de partida la indagación internacional a través de la revisión sistemática en bases de datos Dialnet, Redalyc y Scielo; se localizaron un total de 35 artículos de países de Latinoamérica mediante un proceso de clarificación y con cuatro criterios de inclusión: 1. Búsqueda de estudios en bases de datos en Dialnet, Redalyc y Scielo; 2. Pertenecientes al campo educación en valores en el nivel superior; 3. Investigaciones desarrolladas en los periodos 2013 al 2018, 4. De acceso abierto, se conformó una muestra final de 14 trabajos de investigación. Los hallazgos sostienen la participación de las Instituciones de Educación Superior (IES) para replantear su propósito y compromiso con la sociedad para la formación sólida de profesionistas con valores éticos y morales, la preparación del cuerpo docente que emplee una pedagogía orientada a la buena toma de decisiones y actitudes reflexivas apoyándose de un diseño de escala valoral acorde a las necesidades y contexto económico y social en el alba del siglo XXI, así mismo; se desate la ejecución de políticas educativas orientadas a la educación en valores. Se sugiere para futuras investigaciones la publicación de resultados referentes a la implementación y ejecución de propuestas valorales que los autores sitúan como válidas para el contexto actual.