Search results for "Immobilized enzyme"
showing 10 items of 16 documents
Development of enzymatically-active bacterial cellulose membranes through stable immobilization of an engineered beta-galactosidase
2018
Enzymatically-active bacterial cellulose (BC) was prepared by non-covalent immobilization of a hybrid enzyme composed by a β-galactosidase from Thermotoga maritima (TmLac) and a carbohydrate binding module (CBM2) from Pyrococcus furiosus. TmLac-CBM2 protein was bound to BC, with higher affinity at pH 6.5 than at pH 8.5 and with high specificity compared to the non-engineered enzyme. Both hydrated (HBC) and freeze-dried (DBC) bacterial cellulose showed equivalent enzyme binding efficiencies. Initial reaction rate of HBC-bound enzyme was higher than DBC-bound and both of them were lower than the free enzyme. However, enzyme performance was similar in all three cases for the hydrolysis of 5% l…
Enzymatic biodiesel: Challenges and opportunities
2014
The chemical-catalyzed transesterification of vegetable oils to biodiesel has been industrially adopted due to its high conversion rates and low production time. However, this process suffers from several inherent drawbacks related to energy-intensive and environmentally unfriendly processing steps such as catalyst and product recovery, and waste water treatment. This has led to the development of the immobilized enzyme catalyzed process for biodiesel production which is characterized by certain environmental and economical advantages over the conventional chemical method. These include room-temperature reaction conditions, elimination of treatment costs associated with recovery of chemical…
Improved synthesis of Bn5CpRu(CO)2Cl and its application as racemization catalyst in preparative-scale metalloenzymatic dynamic kinetic resolution of…
2010
An improved gram-scale synthesis of Bn5CpRu(CO)2Cl is reported based on heating of pentabenzylcyclopentadiene with Ru3(CO)12 at 160 °C under argon atmosphere in mesitylene followed by addition of chloroform, continued heating, and evaporation of the solvents. Subsequent washing of unreacted ligand precursor with hexane provided pure title compound in 77 % yield. In combination with Candida antarctica lipase B (CAL-B) (Novozym 435), this complex forms a highly active racemization catalyst for metallo-enzymatic dynamic kinetic resolution (DKR) of secondary alcohols as demonstrated in the present work by converting 100 g of racemic 1-phenylethanol to (R)-1-phenylethanol in >99 % ee and 93 %…
A chemiluminescence flow-based procedure for determination of carbaryl in natural waters exploiting multicommutation and enzymatic reaction
2007
A chemiluminescence procedure for the determination of carbaryl in natural waters using acetylcholinesterase and choline oxidase is described. The flow system designed to implement multicommutation approach controlled by microcomputer comprised five solenoid valves, two columns with immobilized enzymes on controlled pore glass beads and chemiluminometric flow cell. In the best experimental conditions a linear response ranging from 25 to 700 µg L-1 carbaryl was obtained. Water samples were spiked with carbaryl in order to access the accuracy and recoveries between 95 and 101% were obtained for a concentration level ranging from 25 to 100 µg L-1 carbaryl. Detection limit and variation coeffic…
Analytical technique for studying the structure of glycoprotein N-glycans
1993
Abstract The aim of this study was to develop an analytical strategy for the structural analysis of glycoprotein N-glycans by combining several sensitive methods without any elaborate equipment. The following consecutive steps were optimized and applied: (1) immobilization of glycopeptide N-glycosidase F (EC 3.2.2.18) on several polymeric and a silica support, the latter giving a maximum binding capacity of 11.3% of starting activity; (2) lectin affinity chromatography was miniaturized using Mobitec columns of volume 200 μl; the binding capacity of glycoproteins on concanavalin A and wheat germ agglutinin columns was in the range 0.5–1 μg; (3) N-linked oligosaccharides were isolated from co…
Improved antifouling properties and selective biofunctionalization of stainless steel by employing heterobifunctional silane-polyethylene glycol over…
2016
AbstractA straightforward solution-based method to modify the biofunctionality of stainless steel (SS) using heterobifunctional silane-polyethylene glycol (silane-PEG) overlayers is reported. Reduced nonspecific biofouling of both proteins and bacteria onto SS and further selective biofunctionalization of the modified surface were achieved. According to photoelectron spectroscopy analyses, the silane-PEGs formed less than 10 Å thick overlayers with close to 90% surface coverage and reproducible chemical compositions. Consequently, the surfaces also became more hydrophilic, and the observed non-specific biofouling of proteins was reduced by approximately 70%. In addition, the attachment of E…
Revalorization of cellulosic wastes from Posidonia oceanica and Arundo donax as catalytic materials based on affinity immobilization of an engineered…
2020
Catalytic materials obtained by enzyme immobilization have multiple potential applications in the food industry. The choice of the immobilization method and support may be critical to define the properties of the immobilized enzyme compared to the soluble form. Although the use of immobilized enzymes shows multiple advantages, their catalytic efficiency is compromised in many instances. Molecular engineering techniques have been used to generate hybrid proteins where the enzyme of interest is fused to a module with affinity to a specific biopolymer. Binding of the hybrid TmLac-CBM2 protein, in which the β-galactosidase from Thermotoga maritima is fused to a carbohydrate-binding module from …
Hierarchical bimodal porous silicas and organosilicas for enzyme immobilization
2005
This work shows the ability of a hierarchical porous silica-based network with pore systems at two different length scales for enzyme immobilization. Two different enzymes have been selected, lysozyme, a relatively small globular enzyme, and α-L-arabinofuranosidase, a large enzyme of interest in the winemaking industry. The lysozyme immobilization on several silica supports (bimodal porous silicas denoted UVM-7 materials and conventional silica xerogels) has been studied and the loading amounts can be correlated to the open nature and accessibility of the internal surface area. Bimodal UVM-7 silicas present a very quick adsorption rate and high enzyme loading. α-L-Arabinofuranosidase has be…
Matryoshka enzyme encapsulation: Development of zymoactive hydrogel particles with efficient lactose hydrolysis capability.
2019
This report describes an efficient procedure for enzyme encapsulation and its application for the hydrolysis of lactose. The enzymatic material that has been developed consists of hydrogel particles (ca. 3–4 mm of diameter) composed of either alginate or an alginate-agarose combination, in which bacterial cells loaded with a thermostable β-galactosidase are embedded. The cells were rendered fully permeable to the substrate, either chromogenic p-nitrophenyl galactose or lactose, by thermal treatment at 75 °C. Hydrogel particles made of a mixture of alginate and agarose displayed high catalytic activity (i.e. 1 g of beads hydrolyze the lactose equivalent of 100 mL of milk in 15 min) and therm…
Stabilization of anti-leukemic enzyme l-asparaginase by immobilization on polysaccharide levan
2001
Abstract Biologically active fructose polymer levan from Zymomonas mobilis of different molecular mass (75 and 2000 kDa) was covalently coupled to anti-leukemic enzyme Erwinia carotovora l -asparaginase. The method used for the immobilization of the enzyme involved periodate oxidation of the polysaccharide, followed by reductive alkylation. A gentle periodate oxidation of levan (oxidation degree ≤24%) resulted in the highest residual enzyme activity (≥55%). The K m(app.) of glycoconjugates was higher than the K m of native l -asparaginase. The conjugation of l -asparaginase widened the optimum pH range of the enzyme. The electrophoretic mobility in polyacrylamide gel of glycoconjugates obta…