Immobilization of beta-galactosidase and other enzymes onto p-amino-carbanilated cellulose derivatives

Filter paper disks as a matrix for manipulation of recombinant proteins

Filter paper provides an excellent matrix for retention of proteins containing a cellulose binding domain. To use this capability for manipulating recombinant fusion proteins, binding and elution parameters were explored and procedures developed for small scale purification, modification and assay. Proteins were tagged with the cellulose binding domain from the Clostridium thermocellum CipB gene via a cleavable linker. Filter paper disks of 6 mm diameter were able to bind up to 80 μg protein although there was a substantial dependence on molecular size. Different means of introducing fusion proteins to the disks allow either binding within 20 min from microliter volumes or slower binding from milliliter volumes. Elution with protease in small volumes yielded greater than 10 μg amounts with concentrations in the 1-2 mg/ml range. To demonstrate their utility, disks were used for small scale protein purification, covalent modification of protein, immunoprecipitation, and in a binding assay. These versatile methods allow parallel processing of multiple samples and may find many uses when only small amounts of protein are needed.

Stabilization of beta-galactosidase (from peas) by immobilization onto amberlite MB-150 beads and its application in lactose hydrolysis

The soluble PsBGAL (from Pisum sativum ) is extremely unstable with loss of over 80% in enzyme activity within 24 h at 4 degrees C when the protein concentration was lower than 0.1 mg/mL. Enzyme immobilization onto Amberlite MB-150 beads (diameter = 5 microm) greatly stabilized the enzyme preparation, with almost no loss for 12 months at room temperature (27 degrees C). Enzyme (21.9 microg) was immobilized by 62.56% onto activated 100 mg of Amberlite MB-150 beads using 4% glutaraldehyde, at pH 6.0 (50 mM, sodium phosphate buffer). Statistical analysis carried out by ANOVA revealed that all parameters used during immobilization were equally important at P < 0.05 (level of significance). An approach toward commercial exploitation of Amberlite-PsBGAL especially in lactose hydrolysis was anticipated due to improved physicochemical properties including broad optimum pH and temperature, with a K(m) of 4.11 +/- 0.21 mM for lactose. Amberlite-PsBGAL hydrolyzed 64.57 and 69.18% of lactose present in milk and milk whey, respectively, within 10 h (at room temperature). Immobilized enzyme has reusability of over 10 batchwise uses, with almost no loss in activity. The easy accessibility of enzyme source, ease of its immobilization on Amberlite, lower cost of Amberlite, enhanced stability of Amberlite-PsBGAL, and comparable lactose hydrolysis in milk and milk whey described here make it a suitable product for future applications at laboratory and industrial scale.

Immobilization and characterization of beta-galactosidase from the plant gram chicken bean (Cicer arietinum). Evolution of its enzymatic actions in the hydrolysis of lactose

beta-Galactosidase (beta-D-galactosidase galactohydrolase, EC 3.2.1. 23) isolated and purified from gram chicken bean was immobilized on cross-linked polyacrylamide gel. The activity yield was high and attained up to 72%. Compared with the free enzyme, the immobilized enzyme had a wider operational pH range and better thermal stability. Lyophilized pieces exhibited good stability when stored at room temperature for 60 days and a favorable operational stability when used eight times repeatedly without loss of enzymatic activity under the same conditions. Kinetic data (K(m), V(m), and E(a)) for the free and the immobilized enzymes were determined using O-nitrophenyl-beta-D-galactoside (ONPG) and lactose as substrates. The result of time courses of hydrolysis of lactose showed that beta-galactosidase from the plant gram chicken bean would have a promising application in the hydrolysis of lactose in milk.

Polymeric mercaptosilane-modified platinum electrodes for elimination of interferants in glucose biosensors

An oxidase-based glucose sensor has been developed that uses a mercaptosilane-modified platinum electrode to achieve selectivity of electrochemical interferants. A platinum-iridium (9:1) wire (0.178 mm o.d., sensing area of 1.12 mm2) is modified with (3-mercaptopropyl)trimethoxysilane. The modified sensors show excellent operational stability for more than 5 days. Glucose oxidase is immobilized on the modified surface (i) by using 3-maleimidopropionic acid as a linker or (ii) by cross-liking with bovine serum albumin using glutaraldehyde. Sensitivities in the range of 9.97 nA/mM glucose are observed when the enzyme is immobilized by method ii. Lower sensitivities (1.13 x 10(-1) nA/mM glucose) are observed when immobilization method i is employed. In terms of linear response range, the sensor enzyme-immobilized by method i is superior to that immobilized by method ii. The linearity is improved upon coating the enzyme layer with polyurethane. The sensor immobilized by method ii and coated with polyurethane exhibits a linear range to 15 mM glucose and excellent selectivity to glucose (0.47 nA/mM) against interferants such as ascorbic acid, uric acid, and acetaminophen.