Immobilization of a lactase onto a magnetic support by covalent attachment to polyethyleneimine-glutaraldehyde-activated magnetite
- 1 December 1989
- journal article
- research article
- Published by Springer Science and Business Media LLC in Applied Biochemistry and Biotechnology
- Vol. 22 (3), 289-310
- https://doi.org/10.1007/bf02921763
Abstract
A magnetic immobilized lactase has been prepared using magnetite as the magnetic material. Magnetite was functionalized by treatment with polyethyleneimine and crosslinked with glutaraldehyde. Lactase was then covalently coupled to the activated magnetic matrix via the aldehyde groups. The conditions for optimal immobilization of enzyme are described. Eighty percent of the lactase activity was lost on immobilization and is thought to be owing to the orientation of enzyme binding to the matrix. The amount of protein coupled was 80% of that applied. The maximum lactase activity retained on the matrix following immobilization was 360 U/g matrix. The immobilized lactase showed optimal activity at pH 4.5 and 65 °C. The immobilized lactase was more heat stable than the free enzyme, and retained 83% of its original activity after 14 d at 55 °C. Galactose competitively inhibited the immobilized lactase preparation (Ki 20 mM). The presence of high initial concentrations of galactose (10% w/v) did not prevent total hydrolysis of lactose. Glucose and calcium ions were activators of the immobilized enzyme. The immobilized enzyme hydrolyzed high concentrations of lactose (up to 25% w/v) to completion within 4–6 h in a stirred batch reactor at 55 °C. There was no evidence of substrate inhibition at high substrate concentrations. The efficiency of hydrolysis of lactose by the immobilized lactase was better than that of the free enzyme. The magnetic immobilized lactase was demonstrated to be suitable for use in the enzymatic hydrolysis of both pure, and cheese whey permeate, lactose.Keywords
This publication has 22 references indexed in Scilit:
- Kinetic, inhibition, and stability properties of a commercial β‐D‐glucosidase (cellobiase) preparation from aspergillus niger and its suitability in the hydrolysis of lignocelluloseBiotechnology & Bioengineering, 1986
- Some new water purification processes based on polymersProgress in Polymer Science, 1983
- High‐yield method for immobilization of enzymesBiotechnology & Bioengineering, 1980
- Coupling polylysine to glass beads for plasma membrane isolationBiochimica et Biophysica Acta (BBA) - Biomembranes, 1978
- Nonporous magnetic materials as enzyme supports: Studies with immobilized chymotrypsinBiotechnology & Bioengineering, 1977
- Activation of alumina with bovine serum albumin for immobilizing enzymesBiotechnology & Bioengineering, 1975
- Preparation of immobilized lactase. Continued studies on the enzymatic hydrolysis of lactoseBiotechnology & Bioengineering, 1974
- Immobilization of enzymes on magnetic particlesBiotechnology & Bioengineering, 1974
- The preparation of immobilized lactase and its use in the enzymatic hydrolysis of acid wheyBiotechnology & Bioengineering, 1974
- The properties of magnetic supports in relation to immobilized enzyme reactorsBiotechnology & Bioengineering, 1973