title: Immobilization and stabilization of a cyclodextrin glycosyltransferase by covalent attachment on highly activated glyoxyl-agarose supports.
abstract: Covalent immobilization of cyclodextrin glycosyltransferase on glyoxyl-agarose beads promotes a very high stabilization of the enzyme against any distorting agent (temperature, pH, organic solvents). For example, the optimized immobilized preparation preserves 90% of initial activity when incubated for 22 h in 30% ethanol at pH 7 and 40 degrees C. Other immobilized preparations (obtained via other immobilization protocols) exhibit less than 10% of activity after incubation under similar conditions. Optimized glyoxyl-agarose immobilized preparation expressed a high percentage of catalytic activity (70%). Immobilization using any technique prevents enzyme inactivation by air bubbles during strong stirring of the enzyme. Stabilization of the enzyme immobilized on glyoxyl-agarose is higher when using the highest activation degree (75 micromol of glyoxyl per milliliter of support) as well as when performing long enzyme-support incubation times (4 h) at room temperature. Multipoint covalent immobilization seems to be responsible for this very high stabilization associated to the immobilization process on highly activated glyoxyl-agarose. The stabilization of the enzyme against the inactivation by ethanol seems to be interesting to improve cyclodextrin production: ethanol strongly inhibits the enzymatic degradation of cyclodextrin while hardly affecting the cyclodextrin production rate of the immobilized-stabilized preparation.
authors.affiliation: Departamento de Biocatalisis, Instituto de Catalisis-CSIC, Campus UAM, Cantoblanco, Madrid, Spain.
authors.forename: Susana Alicia
authors.initials: SA
authors.lastname: Ferrarotti
authors.forename: Juan M
authors.initials: JM
authors.lastname: Bolivar
authors.forename: Cesar
authors.initials: C
authors.lastname: Mateo
authors.forename: Lorena
authors.initials: L
authors.lastname: Wilson
authors.forename: Jose M
authors.initials: JM
authors.lastname: Guisan
authors.forename: Roberto
authors.initials: R
authors.lastname: Fernandez-Lafuente
mesh_terms: D004800:Enzymes, Immobilized / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry; D005964:Glucosyltransferases / Q000737:chemistry*; D006038:Glyoxylates / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D012685:Sepharose / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D004800:Enzymes, Immobilized; D006038:Glyoxylates; C070399:glyoxyl agarose; D000431:Ethanol; D012685:Sepharose; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase