scispace - formally typeset
Search or ask a question
Topic

Immobilized enzyme

About: Immobilized enzyme is a research topic. Over the lifetime, 15282 publications have been published within this topic receiving 401860 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, the cellulose fiber surfaces were reacted with polyethylene glycol (PEG) diacylchloride to simultaneously add amphiphilic spacers and reactive end groups for coupling with a lipase enzyme.
Abstract: Ultra-high specific surface cellulose fibers with an average diameter of 500 nm were generated from electrospinning and alkaline hydrolysis of cellulose acetate and used as porous supports for enzyme immobilization. The cellulose fiber surfaces were reacted with polyethylene glycol (PEG) diacylchloride to simultaneously add amphiphilic spacers and reactive end groups for coupling with a lipase enzyme. The quantity of reactive carboxylic acid on the fiber surfaces could be readily controlled by COCl/OH molar ratios and PEG lengths. The highest free acid (COOH) content of 1.0 mmol per gram of cellulose was obtained at 10 COCl/OH ratio with the 600-Da PEG diacylchloride. Enzyme coupling on such PEG-attached cellulose was optimal in the presence of a water-soluble carbodiimide [1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)] at a very low EDC/COOH molar ratio of 0.2 under acidic condition and at ambient temperature. Whereas the free lipase retained only 25% of its original activity, the fiber-bound lipase possessed much superior retention of catalytic activity after exposure to cyclohexane (81%) and toluene (62%) and hexane (34%). The fiber-bound lipase also exhibited significantly higher catalytic activity at elevated temperatures than the free form, that is, 10 times at 70 °C. The ultra-fine, fibrous, and porous structures were retained throughout alkaline hydrolysis, activation, coupling, and activity assays. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4289–4299, 2004

117 citations

Journal ArticleDOI
TL;DR: Calibration curves for measurements of cholesterol and cholesterol ester, the effects of pH, temperature, and concomitant compounds, the lifetime of the microsensors, and their availability for measuring cholesterol andolesterol ester in urine were examined.
Abstract: Enzyme microsensors using cholesterol oxidase (EC 1.1.3.6) and cholesterol esterase (EC 3.1.1.13) were developed for measuring cholesterol and cholesterol ester. The platinum microsensors (platinum diameter, 50 microns) were etched in hot aqua regia to create a cavity at their tip. A porous composite material prepared from acetylene black and Teflon emulsion was packed into this cavity and the redox mediator [Os(bpy)3](PF6)2 was monitored by cyclic voltammetry in the potential range of 200-900 mV. The microsensors were dipped overnight in buffer solution containing the desired enzyme to immobilize it on the tip by adsorption. Calibration curves for measurements of cholesterol and cholesterol ester, the effects of pH, temperature, and concomitant compounds, the lifetime of the microsensors, and their availability for measuring cholesterol and cholesterol ester in urine were examined. Under optimal conditions, the response of the sensors was linear in concentration ranges of 5 microM-0.47 mM cholesterol and 2 microM-1.00 mM cholesterol ester.

117 citations

Journal ArticleDOI
TL;DR: It was shown that the amounts of solute adsorption and the immobilization capacity of acid phosphatase on cross-linked chitosan beads were substantially affected by their degree of cross-linking.

117 citations

Journal ArticleDOI
TL;DR: In this paper, the authors compared different types of bacterial cellulose beads for enzyme immobilization and found that the smallest size (0.5-1.5mm) were the best support.
Abstract: Over recent years, there has been a growing interest in the use of cellulose materials in bioprocessing technologies. Bacterial cellulose which is the pure cellulose has unique physical properties which differ from those of plant cellulose and has therefore attracted attention as a new functional material. The applications of bacterial cellulose rarely use the pellet type but it has potential in enzyme immobilization since pellet form is usually used in this field. In this research, Glucoamylase which is widely used in the food industry was immobilized on bacterial cellulose beads after testing using various activation procedures. The results showed that the epoxy method with glutaraldehyde coupling was the best method. After comparison of the different types of bacterial cellulose beads for glucoamylase immobilization, the wet bacterial cellulose beads of the smallest size (0.5–1.5 mm) were the best support. The immobilization of enzyme enhances its stability against changes in the pH value and temperature especially in the lower temperature region. The relative activity of the immobilized glucoamylase was still above 77% at pH 2.0 and it was the highest value in the literature. The relative activities were more than 68% in the lower temperature region even at 20 °C. Thus, bacterial cellulose beads are a practical potential support for the preparation of immobilized enzymes in industrial applications.

117 citations

Patent
Yasusi Niiyama1, Kenshi Sugahara1
25 Nov 1985
TL;DR: In this article, an electrochemical sensor is formed having a working electrode for detecting hydrogen peroxide surrounded by a cylinder portion, and with an enzymecontaining membrane at its tip.
Abstract: An electrochemical sensor is formed having a working electrode for detecting hydrogen peroxide surrounded by a cylinder portion, and with an enzymecontaining membrane at its tip. The membrane has a porous layer permeable to hydrogen peroxide between a layer containing an immobilized enzyme capable of decomposing hydrogen peroxide and a layer containing an immobilized enzyme capable of decomposing a substrate to form hydrogen peroxide. The cylinder portion is embedded in the layer containing the hydrogen peroxide decomposing enzyme and surrounds the working electrode such that the electrode is in contact with the porous layer but is not in contact with the layer containing the hydrogen peroxide decomposing enzyme. The layer containing the hydrogen peroxide forming enzyme is on a side of the porous layer opposite the electrode so as not to contact the electrode. Activity of the hydrogen peroxide decomposing enzyme is no more than one-fourth of the activity of the hydrogen peroxide forming enzyme. The electrochemical sensor reduces base line elevation after measurement action has been discontinued and measurement of a next sample is restarted.

117 citations


Network Information
Related Topics (5)
Cellulose
59K papers, 1.4M citations
84% related
Fermentation
68.8K papers, 1.2M citations
83% related
Aqueous solution
189.5K papers, 3.4M citations
83% related
Ionic liquid
57.2K papers, 1.6M citations
83% related
Adsorption
226.4K papers, 5.9M citations
83% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023219
2022417
2021480
2020548
2019553
2018543