2,703 research outputs found
Release of soybean isoflavones using a β-Glucosidase from Alicyclobacillus herbarius
No full textβ -Glucosidases are used in the food industry to hydrolyse glycosidic bonds in complex sugars, with enzymes sourced from extremophiles better able to tolerate the process conditions. In this work, a novel β-glycosidase from the acidophilic organism Alicyclobacillus herbarius was cloned and heterologously expressed in E. coli BL21 (DE3). Ahe GH1 was stable over a broad range of pH values (5-11) and temperatures (4 oC-55 oC). The enzyme exhibited excellent tolerance to fructose and good tolerance to glucose, retaining 65% activity in the presence of 10% ( w/v ) glucose. It also tolerated organic solvents, some of which appeared to have a stimulating effect, in particular ethanol with a 1.7-fold increase in activity at 10% ( v/v ). The enzyme was then applied for the cleavage of isoflavone from isoflavone glucosides in an ethanolic extract of soy flour, to produce soy isoflavones which constitute a valuable food supplement, achieving full conversion within 15 min at 30 °C
Producing natural vanilla extract from green vanilla beans using a β-glucosidase from Alicyclobacillus acidiphilus
No full textCurrent methods for the production of natural vanilla extract are long and tedious, and the efficiency of the vanillin extraction is usually conditioned by different factors during the traditional curing process (temperatures and weather conditions). As an important fraction of vanillin is present in the form of glucovanillin in green beans, endogenous β-glucosidases contribute to its hydrolysis; however, these enzymes lose efficiency during the curing process. The use of extremophilic organisms as a source of an appropriate exogenous enzyme can offer a valid alternative when producing natural vanillin. Here, a β-glucosidase from the thermo-acidophilic organism Alicyclobacillus acidiphilus (AacGH1) was cloned, expressed in E. coli BL21, and fully characterized in respect to both function and crystal structure. Notably, AacGH1 was stable at a temperature up to 50 °C and exhibited good tolerance to glucose, fructose and organic solvents, in particular it maintained full activity in the presence of up to 20 % (v/v) ethanol. The enzyme was then successfully applied to an ethanol-water (20 % (v/v)) extract of green vanilla beans and the complete hydrolysis of glucovanillin (1.7 mM) to vanillin, and other flavour compounds commonly found in vanilla, was achieved using 0.5 mg/mL of enzyme in just 15 min at 30 °C
An (R)-Selective Transaminase From Thermomyces stellatus: Stabilizing the Tetrameric Form
No full textThe identification and 3D structural characterization of a homolog of the (R)-selective transaminase (RTA) from Aspergillus terreus (AtRTA), from the thermotolerant fungus Thermomyces stellatus (TsRTA) is here reported. The thermostability of TsRTA (40% retained activity after 7 days at 40°C) was initially attributed to its tetrameric form in solution, however subsequent studies of AtRTA revealed it also exists predominantly as a tetramer yet, at 40°C, it is inactivated within 48 h. The engineering of a cysteine residue to promote disulfide bond formation across the dimer-dimer interface stabilized both enzymes, with TsRTA_G205C retaining almost full activity after incubation at 50°C for 7 days. Thus, the role of this mutation was elucidated and the importance of stabilizing the tetramer for overall stability of RTAs is highlighted. TsRTA accepts the common amine donors (R)-methylbenzylamine, isopropylamine, and d-alanine as well as aromatic and aliphatic ketones and aldehydes
Enantio-Complementary Synthesis of 2-Substituted Pyrrolidines and Piperidines via Transaminase-Triggered Cyclizations
No full textChiral N-heterocycles are a common motif in many active pharmaceutical ingredients; however, their synthesis often relies on the use of heavy metals. In recent years, several biocatalytic approaches have emerged to reach enantiopurity. Here, we describe the asymmetric synthesis of 2-substituted pyrrolidines and piperidines, starting from commercially available ω-chloroketones by using transaminases, which has not yet been comprehensively studied. Analytical yields of up to 90% and enantiomeric excesses of up to >99.5% for each enantiomer were achieved, which has not previously been shown for bulky substituents. This biocatalytic approach was applied to synthesize (R)-2-(p-chlorophenyl)pyrrolidine on a 300 mg scale, affording 84% isolated yield, with >99.5% ee.</p
Correspondence to Mary Ann Smith From William H. Borders and C.M. Lowe, March 22, 1961
No full textCorrespondence from William H. Borders and C.M. Lowe to Mary Ann Smith notifying her of a meeting for the Atlanta Student Adult Liaison. 1 page
Three-component velocity measurements in a momentum-conserving, axisymmetric, turbulent jet
No full textExperiments have been performed on a momentum conserving axisymmetric turbulent jet, the turbulence characteristics of which are well known [1]. Simultaneous three-component velocity measurements are acquired with high spatial and temporal resolution, using a new triple-sensor hotwire probe. Velocity and directional calibrations are performed using a dedicated automatic calibration system. Two experiments are performed; one for capturing the average velocity field in a 3D volume, and one for investigating the turbulence spectra in specific points in space. In the first experiment, measurements are performed in 9 equidistant cross-planes, from 10- to 50-diameters downstream of the nozzle using a computer-controlled traversing system. The spatial resolution is as low as 1 mm and the sampling rate was 10 kHz. In the second experiment, long velocity time histories are acquired with 50 kHz sampling rate to perform power spectral density computations for each velocity component. Preliminary results of velocity capture confirm the general characteristics of the turbulent jet. The power spectra at different positions indicate that the turbulent fluctuations are not isotropic at lower frequencies
A General History of the Congregation of the Mission Beginning after the Death of Blessed Vincent de Paul
No full textThis work is the earliest known history of the Congregation of the Mission and dates from about 1730. Vincentian historian John E. Rybolt, C.M., building on the initiative of Stafford Poole, C.M., completed this English translation from the original French. The author, Claude-Joseph Lacour, C.M. (1672-1731), drew from already published materials and his own recollections. While the story he tells may seem familiar, Lacour included materials that are unknown anywhere else and delivers a first-hand account of the Congregation’s rapid growth in those early days. The text is essential reading for anyone wishing to better understand Vincent de Paul’s society of apostolic life of priests and brothers following his death.https://via.library.depaul.edu/vincentian_ebooks/1044/thumbnail.jp
Turbulent separation in lower curved wall channels
No full textTurbulent boundary layer separation in channels with a lower curved wall is studied using direct numerical simulations (DNS). Turbulence dynamics are studied through classical statistical tools such as the turbulent kinetic energy budget for varying lower curved wall dimensions. The geometry features are expected to have a significant effect on the fluid flow structures and the characteristic scales of separation. The separation bubble behind the bump is studied in terms of its size, turbulent kinetic energy production mechanisms and transfer and scale-by-scale energy budget. New innovative data-analysis techniques will be used based on the generalisation of the Kolmogorov equation to anisotropic and spatially non-homogeneous flow configurations
Turbulence modulation in particle laden homogeneous shear flow: Exact Regularized Point Particle method
No full textThis contribution presents a first evaluation of a new approach, dubbed the Exact Regularized Point Particle (ERPP) method [Gualtieri et al., Exact regularized point particle method for multi-phase flows in the two-way coupling regime, arXiv preprint arXiv:1405.6969], designed to model the modulation of turbulence by hundred thousands of small inertial particles. The approach overcomes some intrinsic difficulties which arise in some circumstances in available approaches like, e.g., the Particle In Cell (PIC) method introduced by Crowe and coworkers since 1977. Numerical results concerning a homogeneous shear flow at moderate values of the Reynolds number laden with hundred thousand of small inertial particles are discussed documenting the turbulence modification in the so-called two-way coupling regime, in a range of control parameters unaccessible to the available approaches
The great household in late medieval England
No full textIn the later medieval centuries, a whole range of important social, political, and artistic activities took place against the backdrop of the great English households. In this lively book, C. M. Woolgar explores the fascinating details of life in a great house. Based on extensive investigation of household accounts and related primary documents, Woolgar vividly illuminates the operations of great households. He also delineates the major changes that transformed the economy and geography of both lay and clerical households between 1200 and 1500.In this portrait of aristocratic and gentry life in medieval England, Woolgar describes the roles of family members, the situations of servants, the uses of space within the household, food and drink for daily consumption and for special occasions, furnishing, clothing, arrangements for travel, household animals, cleanliness and hygiene, entertainment, the practices of religion, and intellectual life. The author also analyzes the qualitative and social evolution of great households as definitions of magnificence and conventions of etiquette became increasingly elaborate
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