title: Optimal immobilization of β-galactosidase onto κ-carrageenan gel beads using response surface methodology and its applications.
abstract: β-Galactosidase (β-gal) was immobilized by covalent binding on novel κ-carrageenan gel beads activated by two-step method; the gel beads were soaked in polyethyleneimine followed by glutaraldehyde. 2(2) full-factorial central composite experiment designs were employed to optimize the conditions for the maximum enzyme loading efficiency. 11.443 U of enzyme/g gel beads was achieved by soaking 40 units of enzyme with the gel beads for eight hours. Immobilization process increased the pH from 4.5 to 5.5 and operational temperature from 50 to 55 °C compared to the free enzyme. The apparent K(m) after immobilization was 61.6 mM compared to 22.9 mM for free enzyme. Maximum velocity Vmax was 131.2 μ mol · min(-1) while it was 177.1 μ mol · min(-1) for free enzyme. The full conversion experiment showed that the immobilized enzyme form is active as that of the free enzyme as both of them reached their maximum 100% relative hydrolysis at 4 h. The reusability test proved the durability of the κ-carrageenan beads loaded with β -galactosidase for 20 cycles with retention of 60% of the immobilized enzyme activity to be more convenient for industrial uses.
authors.affiliation: Polymer Department, National Research Centre, El-Behouth Street, Dokki, Cairo 12311, Egypt ; Centre of Scientific Excellence, Group of Biopolymers and Nanobiotechnology, National Research Centre, El-Behouth Street, Dokki, Cairo 12311, Egypt.
authors.forename: Magdy M
authors.initials: MM
authors.lastname: Elnashar
authors.affiliation: Centre of Scientific Excellence, Group of Biopolymers and Nanobiotechnology, National Research Centre, El-Behouth Street, Dokki, Cairo 12311, Egypt ; Chemistry Natural & Microbial Products, National Research Centre, El-Behouth Street, Dokki, Cairo 12311, Egypt.
authors.forename: Ghada E
authors.initials: GE
authors.lastname: Awad
authors.affiliation: Centre of Scientific Excellence, Group of Biopolymers and Nanobiotechnology, National Research Centre, El-Behouth Street, Dokki, Cairo 12311, Egypt ; Chemistry Natural & Microbial Products, National Research Centre, El-Behouth Street, Dokki, Cairo 12311, Egypt.
authors.forename: Mohamed E
authors.initials: ME
authors.lastname: Hassan
authors.affiliation: Polymer Department, Advanced Technology and New Materials Research Institute, City of Scientific Research and Technological Applications, Borg Al-Arab, Alexandria 21934, Egypt.
authors.forename: Mohamed S
authors.initials: MS
authors.lastname: Mohy Eldin
authors.affiliation: Faculty of Science, Al-Azhar University, Cairo 11651, Egypt.
authors.forename: Bakry M
authors.initials: BM
authors.lastname: Haroun
authors.affiliation: Chemistry Natural & Microbial Products, National Research Centre, El-Behouth Street, Dokki, Cairo 12311, Egypt.
authors.forename: Ahmed I
authors.initials: AI
authors.lastname: El-Diwany
mesh_terms: D002351:Carrageenan / Q000737:chemistry*; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000378:metabolism; D005782:Gels; D005976:Glutaral / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008863:Microspheres; D011094:Polyethyleneimine / Q000737:chemistry; D001616:beta-Galactosidase / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004800:Enzymes, Immobilized; D005782:Gels; D002351:Carrageenan; D011094:Polyethyleneimine; D001616:beta-Galactosidase; D005976:Glutaral