scholarly journals Novel Epoxy Activated Hydrogels for Solving Lactose Intolerance

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Magdy M. M. Elnashar ◽  
Mohamed E. Hassan
Keyword(s):  
Lactose Intolerance ◽  
Epoxy Group ◽  
Immobilized Enzymes ◽  
Aldehyde Group ◽  
Medical Problem ◽  
Enzyme Concentration ◽  
Lactose Hydrolysis ◽  
World Population ◽  
Oh Groups ◽  
Michaelis Constants

“Lactose intolerance” is a medical problem for almost 70% of the world population. Milk and dairy products contain 5–10% w/v lactose. Hydrolysis of lactose by immobilized lactase is an industrial solution. In this work, we succeeded to increase the lactase loading capacity to more than 3-fold to 36.3 U/g gel using epoxy activated hydrogels compared to 11 U/g gel using aldehyde activated carrageenan. The hydrogel’s mode of interaction was proven by FTIR, DSC, and TGA. The high activity of the epoxy group was regarded to its ability to attach to the enzyme’s –SH, –NH, and –OH groups, whereas the aldehyde group could only bind to the enzyme’s –NH2group. The optimum conditions for immobilization such as epoxy chain length and enzyme concentration have been studied. Furthermore, the optimum enzyme conditions were also deliberated and showed better stability for the immobilized enzyme and the Michaelis constants,KmandVmax, were doubled. Results revealed also that both free and immobilized enzymes reached their maximum rate of lactose conversion after 2 h, albeit, the aldehyde activated hydrogel could only reach 63% of the free enzyme. In brief, the epoxy activated hydrogels are more efficient in immobilizing more enzymes than the aldehyde activated hydrogel.

Immobilization of ß-galactosidase from Kluyveromyces lactis on Eupergit® C and Properties of the Biocatalyst

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Graciella da Silva Campello ◽  
Renata Aguirre Trindade ◽  
Tatiane Vieira Rêgo ◽  
Janaína Fernandes de Medeiros Burkert ◽  
Carlos André Veiga Burkert
Keyword(s):  
Thermal Stability ◽  
Ionic Strength ◽  
Batch Reactor ◽  
Kluyveromyces Lactis ◽  
Immobilized Enzymes ◽  
Maximum Activity ◽  
Lactose Hydrolysis ◽  
Substrate Affinity ◽  
Burman Design ◽  
Plackett Burman Design

Abstract The main goal of this study was to investigate the immobilization of commercial ß-galactosidase from Kluyveromyces lactis (Lactozym®) on Eupergit® C. A Plackett-Burman design was proposed. The ionic strength and pH were the variables that presented significant effect (p<0.1) on immobilization. The increase in the ionic strength from 0.1 to 1.5 M and the increase in pH from 6.6 to 7.4 represented an increase of 28.56% and a reduction of 18.19% in the immobilization yield, respectively. At 25°C, pH 6.6, ionic strength of 1.5 M, immobilization for 8 h, 1 mM of divalent magnesium ion and 0.4 mL of enzyme added, reached 85% immobilization yield. The free and immobilized enzymes were characterized. pH and temperature profiles showed maximum activity at pH 6.6 and 45°C, for both free and immobilized enzymes. There was a gain in thermal stability with enzyme immobilization and there was an increase of about four times in the half-life of the immobilized derivative at 45°C (from 0.43 h to 1.78 h). This greater thermal stability was also made clear through the calculation of thermodynamic parameters (ΔH, ΔG and ΔS). Km values, 30.33 mM and 104.00 mM for free and immobilized enzymes, respectively, represented a reduction in substrate affinity after immobilization, possibly owing to stereo-conformational factors. In a batch reactor for lactose hydrolysis from cheese whey, an increase in lactose conversion with immobilization was observed at 40°C and 45°C (90.43% and 65.36%, respectively) in relation to the free enzyme (84.17% and 39.58%, respectively).

Oligosaccharide Formation During Enzymatic Lactose Hydrolysis: A Literature Review

1990 ◽  
Vol 53 (3) ◽  
pp. 262-268 ◽  
Author(s):  
S. ZÁRATE ◽  
M. H. LÓPEZ-LEIVA
Keyword(s):  
Literature Review ◽  
Substrate Concentration ◽  
Lactose Intolerance ◽  
Side Reaction ◽  
Point Of View ◽  
Degree Of Conversion ◽  
Lactose Hydrolysis ◽  
Enzyme Source

In the course of lactose hydrolysis and due to the transgalactosydic reaction, the enzyme ß-galactosidase produces variable amounts of oligosaccharides (OS). From a nutritional point of view one has to avoid, or at least, minimize the formation of these OS, because since they are not hydrolyzed by the intestinal ß-galactosidase, these products contribute to the symptoms of lactose intolerance. The effects of enzyme source, substrate concentration, type of process, salts, temperature, pH, and degree of conversion on this side reaction have been reviewed.

scholarly journals Enhancing the Sensing Performance of Zigzag Graphene Nanoribbon to Detect NO, NO2, and NH3 Gases

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3932 ◽  
Author(s):  
Ehab Salih ◽  
Ahmad I. Ayesh
Keyword(s):  
Charge Transfer ◽  
Gas Sensors ◽  
Adsorption Energy ◽  
Gas Adsorption ◽  
Epoxy Group ◽  
Graphene Nanoribbon ◽  
Hydroxyl Group ◽  
Adsorption Parameters ◽  
Oh Groups ◽  
Sensing Performance

In this article, a zigzag graphene nanoribbon (ZGNR)-based sensor was built utilizing the Atomistic ToolKit Virtual NanoLab (ATK-VNL), and used to detect nitric oxide (NO), nitrogen dioxide (NO2), and ammonia (NH3). The successful adsorption of these gases on the surface of the ZGNR was investigated using adsorption energy (Eads), adsorption distance (D), charge transfer (∆Q), density of states (DOS), and band structure. Among the three gases, the ZGNR showed the highest adsorption energy for NO with −0.273 eV, the smallest adsorption distance with 2.88 Å, and the highest charge transfer with −0.104 e. Moreover, the DOS results reflected a significant increase of the density at the Fermi level due to the improvement of ZGNR conductivity as a result of gas adsorption. The surface of ZGNR was then modified with an epoxy group (-O-) once, then with a hydroxyl group (-OH), and finally with both (-O-) and (-OH) groups in order to improve the adsorption capacity of ZGNR. The adsorption parameters of ZGNR were improved significantly after the modification. The highest adsorption energy was found for the case of ZGNR-O-OH-NO2 with −0.953 eV, while the highest charge transfer was found for the case of ZGNR-OH-NO with −0.146 e. Consequently, ZGNR-OH and ZGNR-O-OH can be considered as promising gas sensors for NO and NO2, respectively.

Purification and thermostability of β-galactosidase (lactase) from an autolytic strain of Streptococcus salivarius subsp. thermophilus

1989 ◽  
Vol 56 (1) ◽  
pp. 117-127 ◽  
Author(s):  
Byeong-Seon Chang ◽  
Raymond R. Mahoney
Keyword(s):  
Activation Energy ◽  
Half Life ◽  
Reaction Order ◽  
Specific Activity ◽  
Enzyme Stability ◽  
Enzyme Concentration ◽  
Lactose Hydrolysis ◽  
Streptococcus Salivarius ◽  
First Order

Summaryβ-Galactosidase from an autolytic strain of Streptococcus salivarius subsp. thermophilus was purified 109-fold to near homogeneity. The yield of purified enzyme was 41% and the specific activity was 592 0-nitrophenyl β-D-galactopyranoside U/mg at 37 °C. Two isozymes were present, but only one subunit was detected, having a mol. wt of 116000. Enzyme stability was 37–83 times greater in milk than in buffer in the range 60–65 °C. At 60 °C the half-life in milk was 146 min. Denaturation in buffer was first-order, but in milk the overall reaction order with respect to enzyme concentration was ˜ 0·5. The activation energy for denaturation was 453 kJ/mol in milk and 372 kJ/mol in buffer. In milk the activation energy for lactose hydrolysis was 35·1 kJ/mol.

scholarly journals Highly Efficient Synthesis of 2,5-Dihydroxypyridine using Pseudomonas sp. ZZ-5 Nicotine Hydroxylase Immobilized on Immobead 150

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 548 ◽  
Author(s):  
Caiwen Dong ◽  
Yadong Zheng ◽  
Hongzhi Tang ◽  
Zhangde Long ◽  
Jigang Li ◽  
...  
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Flavin Adenine Dinucleotide ◽  
Immobilized Enzymes ◽  
Enzyme Concentration ◽  
Pseudomonas Sp ◽  
Optimal Conditions ◽  
Efficient Synthesis ◽  
Protein Loading ◽  
Reaction Cycles ◽  
Hydrolysis Of

In this report, the use of immobilized nicotine hydroxylase from Pseudomonas sp. ZZ-5 (HSPHZZ) for the production of 2,5-dihydroxypyridine (2,5-DHP) from 6-hydroxy-3-succinoylpyridine (HSP) in the presence of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) is described. HSPHZZ was covalently immobilized on Immobead 150 (ImmHSPHZZ). ImmHSPHZZ (obtained with 5–30 mg of protein per gram of support) catalyzed the hydrolysis of HSP to 2,5-DHP. At a protein loading of 15 mg g−1, ImmHSPHZZ converted 93.6% of HSP to 2,5-DHP in 6 h. The activity of ImmHSPHZZ was compared with that of free HSPHZZ under various conditions, including pH, temperature, enzyme concentration, substrate concentration and stability over time, and kinetic parameters were measured. The results showed that ImmHSPHZZ performed better over wider ranges of pH and temperature when compared with that of HSPHZZ. The optimal concentrations of ImmHSPHZZ and substrate were 30 mg L−1 and 0.75 mM, respectively. Under optimal conditions, 94.5 mg L−1 of 2,5-DHP was produced after 30 min with 85.4% conversion. After 8 reaction cycles and 6 days of storage, 51.3% and 75.0% of the initial enzyme activity remained, respectively. The results provide a framework for development of commercially suitable immobilized enzymes that produce 2,5-DHP.

scholarly journals Biocatalytic Strategy for Grafting Natural Lignin with Aniline

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 4921
Author(s):  
Sabina Gabriela Ion ◽  
Teodor Brudiu ◽  
Anamaria Hanganu ◽  
Florentina Munteanu ◽  
Madalin Enache ◽  
...  
Keyword(s):  
Gel Permeation Chromatography ◽  
Industrial Applications ◽  
Enzyme Concentration ◽  
Radical Mechanism ◽  
Polymeric Product ◽  
Oh Groups ◽  
Before And After ◽  
Peroxidase Enzyme ◽  
Amine Groups ◽  
Temperature Programmed

This paper presents an enzyme biocatalytic method for grafting lignin (grafting bioprocess) with aniline, leading to an amino-derivatized polymeric product with modified properties (e.g., conductivity, acidity/basicity, thermostability and amino-functionalization). Peroxidase enzyme was used as a biocatalyst and H2O2 was used as an oxidation reagent, while the oxidative insertion of aniline into the lignin structure followed a radical mechanism specific for the peroxidase enzyme. The grafting bioprocess was tested in different configurations by varying the source of peroxidase, enzyme concentration and type of lignin. Its performance was evaluated in terms of aniline conversion calculated based on UV-vis analysis. The insertion of amine groups was checked by 1H-NMR technique, where NH protons were detected in the range of 5.01–4.99 ppm. The FTIR spectra, collected before and after the grafting bioprocess, gave evidence for the lignin modification. Finally, the abundance of grafted amine groups was correlated with the decrease of the free –OH groups (from 0.030 to 0.009 –OH groups/L for initial and grafted lignin, respectively). Additionally, the grafted lignin was characterized using conductivity measurements, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), temperature-programmed desorption (TPD-NH3/CO2) and scanning electron microscopy (SEM) analyses. The investigated properties of the developed lignopolymer demonstrated its disposability for specific industrial applications of derivatized lignin.

scholarly journals Lactose Hydrolysis in Milk and Dairy Whey Using Microbial β-Galactosidases

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Michele Dutra Rosolen ◽  
Adriano Gennari ◽  
Giandra Volpato ◽  
Claucia Fernanda Volken de Souza
Keyword(s):  
Reaction Time ◽  
Food Industry ◽  
Cheese Whey ◽  
Kluyveromyces Lactis ◽  
Enzyme Reaction ◽  
Enzyme Concentration ◽  
Lactose Hydrolysis ◽  
Optimum Temperature ◽  
Whey Permeate ◽  
Hydrolysis Process

This work aimed at evaluating the influence of enzyme concentration, temperature, and reaction time in the lactose hydrolysis process in milk, cheese whey, and whey permeate, using two commercial β-galactosidases of microbial origins. We used Aspergillus oryzae (at temperatures of 10 and 55°C) and Kluyveromyces lactis (at temperatures of 10 and 37°C) β-galactosidases, both in 3, 6, and 9 U/mL concentrations. In the temperature of 10°C, the K. lactis β-galactosidase enzyme is more efficient in the milk, cheese whey, and whey permeate lactose hydrolysis when compared to A. oryzae. However, in the enzyme reaction time and concentration conditions evaluated, 100% lactose hydrolysis was not reached using the K. lactis β-galactosidase. The total lactose hydrolysis in whey and permeate was obtained with the A. oryzae enzyme, when using its optimum temperature (55°C), at the end of a 12 h reaction, regardless of the enzyme concentration used. For the lactose present in milk, this result occurred in the concentrations of 6 and 9 U/mL, with the same time and temperature conditions. The studied parameters in the lactose enzymatic hydrolysis are critical for enabling the application of β-galactosidases in the food industry.

scholarly journals ENZYMATIC BREAKDOWN OF THREONINE BY THREONINE ALDOLASE

1954 ◽  
Vol 38 (2) ◽  
pp. 181-196 ◽  
Author(s):  
Shih-Chia C. Lin ◽  
David M. Greenberg
Keyword(s):  
Pyridoxal Phosphate ◽  
Thermal Inactivation ◽  
Enzyme Reaction ◽  
Enzyme Concentration ◽  
Ph Optimum ◽  
First Order ◽  
Threonine Aldolase ◽  
First Order Kinetics ◽  
Michaelis Constants ◽  
Tris Maleate

1. The enzyme which splits threonine to acetaldehyde and glycine has been partially purified from rat liver (five- to sixfold purification) and the name threonine aldolase proposed for it. 2. The general properties of threonine aldolase have been studied. The enzyme is unstable to a pH below 5. The pH optimum of the enzyme reaction is at 7.5–7.7. The initial rate of production of acetaldehyde is proportional to the enzyme concentration, and when the enzyme concentration is constant, the production of acetaldehyde is proportional to the time, provided that the substrate is in excess. The enzyme is inhibited by the carbonyl group reagent, hydroxylamine. Attempts to demonstrate that pyridoxal phosphate is a cofactor were unsuccessful. 3. The enzyme splits only L-allothreonine and L-threonine and is inactive against the D-forms of these amino acids. 4. The enzyme reaction on DL-allothreonine follows first order kinetics. From the first order velocity constants and the initial rates of the rates of the reaction at various substrate concentrations the Michaelis constant, Ks, for this substrate has been evaluated. Michaelis constants have also been determined for threonine. 5. The optimum temperature for the enzymatic breakdown of DL-allothreonine at pH 7.65 was found to be 50°C. in phosphate buffer and 48°C. in tris-maleate buffer. The rate of thermal inactivation of the enzyme threonine aldolase obeys a first order reaction. The heat of thermal inactivation was calculated by the aid of the van't Hoff-Arrhenius equation to be 43,000 cal. per mole for the temperature range 41.2–46.6°C. 6. Equivalent amounts of acetaldehyde and glycine were formed from DL-allothreonine and the enzymatic breakdown of DL-allothreonine was found to be irreversible.

scholarly journals Gestational Hypertension and Organophosphorus Pesticide Exposure: A Cross-Sectional Study

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Caterina Ledda ◽  
Maria Fiore ◽  
Lory Santarelli ◽  
Massimo Bracci ◽  
Giuseppe Mascali ◽  
...  
Keyword(s):  
Occupational Exposure ◽  
Pesticide Exposure ◽  
Gestational Hypertension ◽  
Organophosphorus Pesticide ◽  
First Trimester ◽  
Medical Problem ◽  
Cross Sectional Study ◽  
World Population ◽  
Sectional Study ◽  
Cross Sectional

Hypertension is the most common medical problem encountered during pregnancy, complicating 2-3% of pregnancies. High blood pressure (BP) with diastolic BP ≥ 90 mm Hg and/or systolic BP ≥ 140 mm Hg arising after week 22 of pregnancy and resolving after delivery is defined as gestational hypertension (GHY). The aim of this cross-sectional study was to investigate whether occupational and/or environmental exposure to organophosphorus (OP) pesticide affects GHY. Women at approximately 22 weeks of gestation were recruited. OP pesticide exposure in the first trimester of pregnancy was classified into four categories: no exposure, indirect exposure, domestic exposure, and occupational exposure. Application of the exclusion criteria left 2203 participants (mean age 30.4 ± 11.6 years). Data analysis showed that in women with indirect OP pesticide exposure the incidence of GHY was slightly higher than that in the world population, whereas domestic exposure involved a 7% increase and occupational exposure a 12% increase. Analysis of the pesticides used by participants highlighted a possible role for malathion and diazinon (adjusted OR 1.09 and 1.14, resp.). Further investigation of exposed workers and the general population is clearly warranted given the broad diffusion of OP pesticides and their possible public health impact, maybe by including a wider range of health outcomes.

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