title: Macromolecular cross-linked enzyme aggregates (M-CLEAs) of α-amylase.
abstract: Macromolecular cross-linked enzyme aggregates (M-CLEAs) of α-amylase were prepared by precipitation and subsequent cross-linking. The non-toxic, biodegradable, biocompatible, renewable polysaccharide based macromolecular cross-linkers viz. agar, chitosan, dextran, and gum arabic were used as a substitute for traditional glutaraldehyde to augment activity recovery toward macromolecular substrate. Macromolecular cross-linkers were prepared by periodate mediated controlled oxidation of polysaccharides. The effects of precipitating agent, concentration and different cross-linkers on activity recovery of α-amylase CLEAs were investigated. α-Amylase aggregated with ammonium sulphate and cross-linked by dextran showed 91% activity recovery, whereas glutaraldehyde CLEAs (G-CLEAs) exhibited 42% activity recovery. M-CLEAs exhibited higher thermal stability in correlation with α-amylase and G-CLEAs. Moreover, dextran and chitosan M-CLEAs showed same affinity for starch hydrolysis as of free α-amylase. The changes in secondary structures revealed the enhancements in structural and conformational rigidity attributed by cross-linkers. Finally, after five consecutive cycles dextran M-CLEAs retained 1.25 times higher initial activity than G-CLEAs.
authors.affiliation: Department of Chemical Engineering, Institute of Chemical Technology, Matunga (E), Mumbai 400019, India. Electronic address: ce14ss.nadar@pg.ictmumbai.edu.in.
authors.forename: Shamraja S
authors.initials: SS
authors.lastname: Nadar
authors.affiliation: Department of Food Technology, University Institute of Chemical Technology, North Maharashtra University, Jalgaon 425001, India.
authors.forename: Abhijeet B
authors.initials: AB
authors.lastname: Muley
authors.affiliation: Department of Food Technology, University Institute of Chemical Technology, North Maharashtra University, Jalgaon 425001, India.
authors.forename: Mayur R
authors.initials: MR
authors.lastname: Ladole
authors.affiliation: Department of Biotechnology Engineering, Kolhapur Institute of Technology's College of Engineering, Gokul Shirgaon, Kolhapur 416 234, India.
authors.forename: Pranoti U
authors.initials: PU
authors.lastname: Joshi
mesh_terms: D003432:Cross-Linking Reagents; D004789:Enzyme Activation; D004800:Enzymes, Immobilized; D010084:Oxidation-Reduction; D066329:Protein Aggregates; D013379:Substrate Specificity; D013816:Thermodynamics; D000516:alpha-Amylases / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D066329:Protein Aggregates; D000516:alpha-Amylases
keywords: Cross-linkers; Glutaraldehyde; Immobilization; Macromolecular substrate; α-Amylase CLEAs