Nylon-immobilized enzymes, activity

Figure 1. Activity Profile for Nylon Immobilized Enzymes.

Active immobilized enzymes for the transformation of steroid in water-organic solvent systems Study of properties of the active immobilized enzyme Active immobilized enzyme Development of a nylon tube reactor for the analytical determination of creatinine and creatine... 

A portable disposable bioprobe for detection and semiquantitative determination of phenols consists of a mushroom polyphenol oxidase immobilized on a nylon membrane, acting in the presence of 3-methyl-2-benzothiazolinone hydrazone. Maroon to orange colored dyes of (138) are developed, as illustrated for phenol (equation 6), of intensity proportional to the concentration of the substrate, down to 0.05 mgL. Enzyme activity remained unscathed in the pH range 4 to 10, in the presence of various concentrations of salt and metal ions and at temperatures from 5 to 25... 

In most amperometric cytochrome b2 electrodes the reaction is followed by anodic oxidation of ferrocyanide at a potential of +0.25 V or above. The first of such sensors was assembled by Williams et al. (1970), who immobilized the enzyme (from baker s yeast) physically at the tip of a platinum electrode within a nylon net of 0.15 mm thickness. The large layer thickness resulted in a response time of 3-10 min. Owing to the low specific enzyme activity used, the sensor was kinetically controlled. Therefore the linear measuring range extended only up to 0.1 Km-A similar sensor has been applied by Durliat et al. (1979) to continuous lactate analysis. The enzyme was contained in a reaction chamber of 1 pi volume in front of the electrode. This principle has also been employed in the first commercial lactate analyzer using an enzyme electrode (Roche LA 640, see Section 5.2.3.3X With a sensor stability of 30 days and a C V below 5%, 20-30 samples/h can be processed with this device. 

Immobilized enzyme nylon tube reactor 775 for the routine analysis of serum D-glucose Investigation of properties of active 776... 

Enzyme nylon tube reactor for routine determination of lactate in serum Active immobilized enzyme evaluation of potential of immobilized enzyme in the iodination of small molecules Investigation of the active site of the immobilized enzyme... 

Reaction with nylon imidate Active immobilized enzyme 750 ... 

Glutaraldehyde cross-linking with albumin onto a nylon grating Investigation of the effects of an electric field on the activity of the immobilized enzyme membrane 820... 

The inner surface of nylon tubing has been activated with dimethylsulphate and then treated with L-lysine. After activation of the derivatized surface with glutaraldehyde or dimethyl adipimidate, neuraminidase was covalently linked to the surface of the tubing. The stability of the active immobilized enzyme was investigated and its potential application for release of neuraminic acid from surfaces of leukaemic AKR mouse thymus and spleen lymphocytes evaluated. 

Matrices for enzyme immobilization on nylon tubes, nylon-covered glass and packed reactors have been investigated in detail [369]. The results have shown that nylon-supported enzymes are less active but easier to use than those supported on glass whiskers . 

Adsorption onto carbon and cross-linking with glutaraldehyde is unsuitable for the immobilization of p-D-galactosidase, since it results in loss of enzymic activity 34s p.D-Galactosidase immobilized on nylon tubing can be used for the continuous hydrolysis of lactose. An activity half-life of 100 days has been reported for p-D-galactosidase immobilized on feather-meal protein. ... 

Pahujani, S., S. S. Kanwar, G. Chauhan, and R. Gupta. 2008. Glutaraldehyde Activation of Polymer Nylon-6 for Lipase Immobilization Enzyme Characteristics and Stability. ... 

Physical adsorption and covalent attachment of both native and reconibinant OPH onto various supports such as nylon membranes, porous glass and nanometer size silica beads have been enqiloyed (3,21,22).. Unfortunately, physical adsorption offers poor and nonspecific binding, vdiile coval modifications to OPH often results in reduction of enzyme activity and kinetic properties (22,23). In addition to reducing catalytic activity, there is no controlled orientation of the immobilized enzymes, leading to inaccessibility of the substrate to the enzyme active site. In the case of covalent bondii, the immobilization support is not reusable since the formed covalent bond is irreversible. In addition, the tedious and costly protocol for purification of OPH limits its use in large-scale enzymatic degradation. 

Covalent immobilization of lipase on nylon fibers has been done, using the enzymes carbohydrate groups as chemical link. Oxidation of the lipases carbohydrates with periodate provides aldehyde groups for the binding to hydrazide activated nylon (Lopez, Braun Klein, 1996). 

The immobilization process, however, can be complicated. The immobilization of an enzyme on nylon serves as a point of comparison. The first step is to activate the surface of the nylon by treating it with hydrochloric acid at room temperature for 24 hours. The partially hydrolyzed nylon is then dried in ether and stored in a desiccator overnight. The nylon is then mixed with a coupling agent [l-ethyl-3-(3-dimethyaminopropyl)] and shaken for 1 hour. The enzyme is then added and shaken overnight at 4 C. 

Two main criteria for the membrane selection are pore size and material. As peroxidases usually have sizes in the range of 10-80 kDa, ultrafiltration membranes with a molecular cutoff between 1 and 50 kDa are the most adequate to prevent enzyme leakage [99]. The materials commonly applied to ultrafiltration membranes are synthetic polymers (nylon, polypropylene, polyamide, polysulfone, cellulose and ceramic materials [101]. The adequate material depends on a great number of variables. When enzyme is immobilized into the matrix, this must be prepared at mild conditions to preserve the enzymatic activity. In the case of enzyme immobilization onto the membrane, this should be activated with the reactive groups necessary to interact with the functional groups of the enzyme. If an extractive system is considered, the selection of the hydrophilicity or hydro-phobicity of the membrane should be performed according to the features of reactants, products, and solvents. In any case, the membrane should not interfere with the catalytic integrity of the enzyme. 

The first electrode for urea was prepared by immobilizing urease in a poly-acrylcimide gel on nylon or Dacron nets. The nets were placed onto a Beckman electrode (NH J selective) (59). In a later development, the electrode was improved by covering the enzyme gel layer with a cellophane membrane to prevent leaching of urease into the solution (60). The urease electrode could be used for 21 days with no loss of activity. 

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