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Metabolism
Published in Volodymyr Ivanov, Environmental Microbiology for Engineers, 2020
The velocity of reactions is used for the quantification of an enzyme through enzymatic activity, in terms of the enzyme unit (U), which is the amount of enzyme that catalyzes the conversion of 1 µmole of substrate per minute under optimal conditions. Empirical enzyme units are used in engineering: for example, velocities of the changes in optical density or viscosity of the medium, or the increase in product concentration in the medium. The rate of biochemical reaction can be given as mol of substrate g−1 of biomass s−1 or as mol of substrate L−1 s−1.
Evaluation of bezafibrate, gemfibrozil, indomethacin, sulfamethoxazole, and diclofenac removal by ligninolytic enzymes
Published in Preparative Biochemistry & Biotechnology, 2020
Dante Camarillo Ravelo, Octavio Loera Corral, Ignacio González-Martínez, Wilberth Chan Cupul, Celestino Odín Rodríguez Nava
Enzyme activities were determined spectrophotometrically using a DR 5000 UV-spectrophotometer (HACH, Denver, USA) at room temperature (25–27 °C). Lac activity was determined by measuring the oxidation of 2, 2′-azino-bis (3-ethylbenzthiazoline-6- sulfonic acid) (ABTS) as described by More et al.[22] and Chan-Cupul et al.[14] In a reaction mixture (1 mL) containing 100 µL of ABTS (0.5 mM), 800 µL of acetate buffer (100 mM, pH 4.5) and 100 µL of enzyme extract. Absorbance changes in the presence of the enzyme were monitored for 5 min at 420 nm (ε = 3.6 × 104/M/cm). One unit of Lac activity was defined as the amount of enzyme required to oxidize 1 µmol ABTS per min per mg of protein under the assay conditions. MnP activity was determined at 610 nm (ε = 4460/M/cm) using the methodology described by Kuwahara et al.[23] The reaction mixture contained 700 µL of the enzyme extract, 50 µL of phenol red 0.2%, 50 µL of sodium lactate 0.5 mM, 50 µL of egg albumin 0.1%, 50 µL of manganese sulfate 2 mM and 50 µL of hydrogen peroxide 2 mM. The reaction was carried out in 50 µL of sodium succinate buffer (20 mM) at pH 4.5 for 5 min. It was stopped by the addition of 50 µL of NaOH (2 N). One enzyme unit was defined as 1 µmol of product formed per min per mg of protein under the assay conditions. Lignin peroxidase activity was determined according to Tien and Kirk[24] at 310 nm (ε = 9300/M/cm). The reaction solution included 200 µL of 10 mM veratryl alcohol, 500 µL enzyme sample and 200 µL of 0.25 M sodium tartrate buffer (pH 2.5). The reaction was initiated by adding 100 µL of H2O2 (1%). One unit (U) of lignin peroxidase activity was defined as the amount of enzyme required to produce 1 µmol of veratryl aldehyde in 1 min at 30 °C. The protein content of the extracts was estimated according to the Bradford method.[25]
A novel basydiomycete isolated from mangrove swamps in the Colombian Caribbean shows promise in dye bioremediation
Published in Bioremediation Journal, 2022
Laura M. Jutinico-Shubach, Jesús D. Castaño, Tulio Juarez, Miguel Mariño, Javier Gómez-León, Lina M. Blandón
All enzymatic assays were measured spectrophotometrically in a MultiskanTM GO Microplate Spectrophotometer (Thermo Scientific®). The enzymatic activities were expressed in UL−1 and obtained as the mean of three biological replicates. One enzyme unit (U) was defined as the amount of enzyme required to produce 1.0 μmol of product per minute under the assay conditions.
Enzymatic biodegradation, kinetic study, and detoxification of Reactive Red-195 by Halomonas meridiana isolated from Marine Sediments of Andaman Sea, India
Published in Environmental Technology, 2023
Purbasha Saha, Sonal Madliya, Anmol Khare, Ikshita Subudhi, Kokati Venkata Bhaskara Rao
Quantitative assays were used to estimate the amount of enzymes. An enzyme unit has been defined as the enzyme quantity that catalyses the conversion of 1 µmol of the substrate to product/min under specified experimental conditions. Enzyme assays were carried out in triplicates.