A method for monitoring blood glucose levels at frequent intervals, which includes a method for equalizing the temperature and oxygen level in the blood and sensing the rate of oxygen consumption by the glucose contained in the blood in the presence of glucose oxidase enzyme immobilized on a hydrophobic membrane covering a measurement electrode and elements employed therein including the equalizing method and the electrode and method for preparing same.

Method for monitoring blood glucose levels and elements

Porous glass as a solid support for immobilisation or affinity chromatography of enzymes.

Publisher Summary This chapter discusses the kinetic behavior of immobilized enzyme systems. In the case of immobilized enzymes, the kinetic behavior can be controlled by both microenvironmental and mass-transfer effects. It is useful to distinguish between intrinsic rate parameters of the enzymic reaction—that is, the kinetic parameters characteristic of the native enzyme in solution. The techniques commonly employed for the characterization of diffusional resistances and the evaluation of the intrinsic or inherent kinetic parameters of immobilized enzyme systems are classified in three main groups: direct determination of kinetic and transport parameters, variation of substrate concentration, and variation of characteristic support dimensions.

[29] Kinetic behavior of immobilized enzyme systems

Glucose oxidase (EC 1.1.3.4) is the most widly employed enzyme as analytical reagent. This is the result of (1) its utility in the determination of glucose, an analyte of wide analytical interest, and (2) its relatively low cost and good stability that make the glucose/glucose oxidase system a very convenient model for method development (particularly in the area of biosensors). This review discusses in detail enzyme structure, biocatalysis, enzymes as analytical reagents, properties of glucose oxidase (including a historical account), and the use of glucose oxidase as an analytical reagent in homogeneous systems as well as an immobilized reagent.

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Glucose Oxidase as an Analytical Reagent

A catheter (12) having a therapeutic agent chemically bonded to a substrate (16) on its exterior surface using a linker (18) which photolytically releases the agent upon exposure to light energy at an appropriate wavelength. The linker (18) is attached to the substrate (16) via a complementary chemical group, with the opposing end containing an aromatic ring with a nitro group in the ortho position relative to a methyl or ethyl group which is functionalized to accept a complementary bond to the therapeutic agent (20). The substrate (16) may include materials such as glass, polyamide, polyester, polyolefin, polypropylene, polyurethane, or latex. The therapeutic agent (20) may include peptides, proteins, steroids, carbohydrates, nucleotides, or other alipathic or heterocyclic products, and may be bonded to a molecular lattice or meshwork to accomodate a high molecular concentration per unit area and the inclusion of ancillary compounds such as markers or secondary emitters.

Catheter system for controllably releasing a therapeutic agent at a remote tissue site

1. Glucose oxidase (EC 1.1.3.4) and urease (EC 3.5.1.5) were covalently attached through glutaraldehyde to low-molecular-weight nylon powder. 2. Immobilized derivatives of glucose oxidase and urease were prepared by cross-linking the respective enzymes within the matrix of a nylon membrane. 3. An improved process is described for the immobilization of glucose oxidase and urease on the inside surface of partially hydrolysed nylon tube. 4. Automated analytical procedures are described for the determination of glucose with each of the three immobilized glucose oxidase derivatives and for the determination of urea with each of the three immobilized urease derivatives. 5. The efficiencies of the three immobilized enzyme structures as reagents for the automated determination of their substrates were compared.

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The immobilization of enzymes on nylon structures and their use in automated analysis.

1. A process is described for the chemical attachment of an enzyme to the surface of a polystyrene matrix. 2. By this process yeast β-fructofuranosidase was chemically attached to the surface of both polystyrene beads and polystyrene tubes. 3. The kinetics of sucrose hydrolysis by β-fructofuranosidase and polystyrene-supported β-fructofuranosidase were compared. 4. The pH–activity curve of the polystyrene-supported enzyme shows a marked difference from that of the free enzyme in solution. 5. The inhibitor dissociation constant with respect to tris is increased, whereas the inhibitor dissociation constant with respect to aniline is decreased when the enzyme is attached to polystyrene. 6. Differences between the properties of the bound and free enzyme are discussed in terms of a micro-environmental effect arising from the hydrophobic nature of the polystyrene support.

The preparation and properties of yeast β-fructofuranosidase chemically attached to polystyrene

1. Glucose oxidase (EC 1.1.3.4), amyloglucosidase (EC 3.2.1.3), invertase (EC 3.2.1.26) and β-galactosidase (EC 3.2.1.23) were covalently attached via glutaraldehyde to the inside surface of nylon tube. 2. The linked enzyme system, comprising invertase immobilized within a nylon tube acting in series with glucose oxidase immobilized in a similar way, was used for the automated determination of sucrose. 3. The linked enzyme system, comprising β-galactosidase immobilized within a nylon tube acting in series with glucose oxidase immobilized in a similar way, was used for the automated determination of lactose. 4. The linked enzyme system, comprising amyloglucosidase immobilized within a nylon tube acting in series with glucose oxidase immobilized in a similar way, was used for the automated determination of maltose. 5. Mixtures of glucose oxidase and amyloglucosidase were immobilized within the same piece of nylon tube and used for the automated determination of maltose. 6. Mixtures of glucose oxidase and invertase were immobilized within the same piece of nylon tube and used for the automated determination of sucrose.

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W. E. Hornby

Papers

The immobilization of enzymes on nylon structures and their use in automated analysis.

The preparation and properties of yeast β-fructofuranosidase chemically attached to polystyrene

Preparation of some immobilized linked enzyme systems and their use in the automated determination of disaccharides.