scholarly journals Synthesis of Sol-Gel Matrices for Encapsulation of Enzymes Using an Aqueous Route

1998 ◽  
Vol 519 ◽  
Author(s):  
R.B. Bhatia ◽  
C.J. Brinker ◽  
C.S. Ashley ◽  
T.M. Harris
Keyword(s):  
Hydrogen Peroxide ◽  
Glucose Oxidase ◽  
Sol Gel ◽  
Enzymatic Reactions ◽  
Host Materials ◽  
Colored Product ◽  
Silicate Matrices ◽  
Kinetics Of ◽  
Oxidation Of Glucose ◽  
Biosensor Applications

AbstractSol-gel matrices are promising host materials for potential chemical and biosensor applications. Previous studies have focused on modified sol-gel routes using alkoxides for encapsulation of enzymes. However the formation of alcohol as a byproduct during hydrolysis and condensation reactions poses limitations. We report the immobilization of glucose oxidase and peroxidase in silica prepared by an aqueous route which may provide a more favorable environment for the biomolecules. A two step aqueous sol-gel procedure using sodium silicate as the precursor was developed to encapsulate the enzymes and the dye precursor, o-dianisidine. Glucose oxidase catalyzes the oxidation of glucose to give gluconic acid and hydrogen peroxide. Peroxidase then catalyzes the reaction of the dye precursor with hydrogen peroxide to produce a colored product. The kinetics of the coupled enzymatic reactions were monitored by optical spectroscopy and compared to those occurring in tetramethyl orthosilicate (TMOS) derived silica matrices developed by Yamanaka et al. [1]. Enhanced kinetics in the aqueous silicate matrices were related to differences in the host microstructures as elucidated by microstructural comparisons of the corresponding aerogels.

Collaborative Study of Enzymatic Glucose Determination in Corn Starch Hydrolysates

1969 ◽  
Vol 52 (3) ◽  
pp. 556-559
Author(s):  
J T Brady ◽  
J A Zagorski
Keyword(s):  
Hydrogen Peroxide ◽  
Gas Chromatography ◽  
Glucose Oxidase ◽  
Glucose Concentration ◽  
Corn Starch ◽  
Collaborative Study ◽  
Color Intensity ◽  
Glucose Determination ◽  
Colored Product ◽  
Oxidation Of Glucose

Abstract Glucose in starch hydrolysates was determined by catalytic oxidation of glucose with glucose oxidase to form hydrogen peroxide which, in the presence of peroxidase and a chromogen, yields a colored product. This product, when acidified, is very stable and the color intensity is proportional to the glucose concentration in the sample. Fermco Test S.F.G., a package containing all the ingredients necessary for the reaction, was used. Eleven collaborators who analyzed five different sirup samples found the method to be adequate for determining glucose. Results compared well with those by paper and gas chromatography. The method is recommended for adoption as official first action.

Nitroalkanes as Reductive Substrates for Flavoprotein Oxidases

1972 ◽  
Vol 27 (9) ◽  
pp. 1052-1053 ◽  
Author(s):  
David J. T. Porter ◽  
Judith G. Voet ◽  
Harold J. Bright
Keyword(s):  
Hydrogen Peroxide ◽  
Amino Acid ◽  
Glucose Oxidase ◽  
Ph Dependence ◽  
Kinetic Mechanism ◽  
Acid Oxidase ◽  
Amino Acid Oxidase ◽  
Kinetics Of ◽  
Oxidase Reaction ◽  
Detailed Kinetic Mechanism

Nitroalkanes have been found to be general reductive substrates for D-amino acid oxidase, glucose oxidase and L-amino acid oxidase. These enzymes show different specificities for the structure of the nitroalkane substrate.The stoichiometry of the D-amino acid oxidase reaction is straightforward, consisting of the production of one mole each of aldehyde, nitrite and hydrogen peroxide for each mole of nitroalkane and oxygen consumed. The stoichiometry of the glucose oxidase reaction is more complex in that less than one mole of hydrogen peroxide and nitrite is produced and nitrate and traces of 1-dinitroalkane are formed.The kinetics of nitroalkane oxidation show that the nitroalkane anion is much more reactive in reducing the flavin than is the neutral substrate. The pH dependence of flavin reduction strongly suggests that proton abstraction is a necessary event in catalysis. A detailed kinetic mechanism is presented for the oxidation of nitroethane by glucose.It has been possible to trap a form of modified flavin in the reaction of D-amino acid oxidase with nitromethane from which oxidized FAD can be regenerated in aqueous solution in the presence of oxygen.

scholarly journals Glucose biosensor based on entrapment of glucose oxidase and myoglobin in silica gel by the sol-gel method

2005 ◽  
Vol 19 (2) ◽  
pp. 119-126 ◽  
Author(s):  
Mohammed A. Zaitoun
Keyword(s):  
Hydrogen Peroxide ◽  
Glucose Oxidase ◽  
Glucose Concentration ◽  
Decay Curve ◽  
Sol Gel ◽  
Porous Silica ◽  
Glucose Biosensor ◽  
Negative Peak ◽  
Before And After ◽  
Porous Silica Glass

A spectrophotometric method is presented to determine glucose employing the sol-gel technique. Myoglobin (Mb) and glucose oxidase are encapsulated in a transparent and porous silica glass. The produced gel (xerogel) is then immersed in water where increments of glucose are added to the solution with stirring; glucose diffuses into the sol-gel glass pores and a series of reactions take place. Glucose is first oxidized by glucose oxidase and oxygen to gluconate and hydrogen peroxide is generated. The liberated hydrogen peroxide oxidizes the Mb heme (Fe2+into Fe3+). The higher is the glucose concentration added, the more is the H2O2generated, and the more is the Mb oxidation (Fe2+to Fe3+) and as a result the higher is the absorbance at 400 nm (negative peak, lower absorbance value). All measurements are performed at this wavelength (400 nm), the negative peak obtained by subtracting the absorption spectra of Mb before and after oxidation. Measuring the slope of the absorbance decay versus time at 400 nm monitors increments of added glucose. Each glucose concentration has an accompanying unique decay curve with a unique slope. The higher is the glucose concentration; the steeper is the decay curve (higher slope value). The calibration curve was linear up to 40 mM.

scholarly journals Haemichrome formation from haemoglobin subunits by hydrogen peroxide

1978 ◽  
Vol 171 (2) ◽  
pp. 329-335 ◽  
Author(s):  
A Tomoda ◽  
K Sugimoto ◽  
M Suhara ◽  
M Takeshita ◽  
Y Yoneyama
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Glucose Oxidase ◽  
Xanthine Oxidase ◽  
Absorption Spectra ◽  
Human Haemoglobin ◽  
Kinetics Of

The effect of H2O2 on ferrous human haemoglobin subunits (alphash-, betash-, alphapmb- and betapmb-chains) was studied. These chains were easily transformed to haemichrome by the addition of H2O2 or H2O2-generating systems, including glucose oxidase (EC 1.1.3.4) AND XANTHINE OXIDASE (EC 1.2.3.2), and this was ascertained by e.p.r. measurements and by absorption spectra. The changes in these haemoglobin subunits were not inhibited by superoxide dismutase (EC 1.15.1.1), but were decreased by catalase (EC 1.11.1.6). The rate of oxidation of alphapmb-chains was higher than that of alphash-chains, and the rate of oxidation of betapmb-chains was higher than that of betash-chains. Haemichrome was demonstrated to be formed directly from these ferrous chains by the attack by H2O2, and this process did not involve formation of methaemoglobin. On the basis of these findings the kinetics of the reaction between the haemoglobin subunits and H2O2 was studied, and the pathological significance of H2O2 in disorders of erythrocytes such as thalassaemia was discussed.

scholarly journals Approximation theorems of a solution of amperometric enzymatic reactions based on Green’s fixed point normal-S iteration

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Khanitin Muangchoo-in ◽  
Kanokwan Sitthithakerngkiet ◽  
Parinya Sa-Ngiamsunthorn ◽  
Poom Kumam
Keyword(s):  
Fixed Point ◽  
Boundary Value Problems ◽  
Iterative Methods ◽  
Dynamical Problem ◽  
Enzymatic Reactions ◽  
Nonlinear Dynamical ◽  
Numerical Examples ◽  
Approximation Theorems ◽  
Kinetics Of ◽  
Nonlinear Dynamical Problem

AbstractIn this paper, the authors present a strategy based on fixed point iterative methods to solve a nonlinear dynamical problem in a form of Green’s function with boundary value problems. First, the authors construct the sequence named Green’s normal-S iteration to show that the sequence converges strongly to a fixed point, this sequence was constructed based on the kinetics of the amperometric enzyme problem. Finally, the authors show numerical examples to analyze the solution of that problem.

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