title: Stabilization of Aspergillus parasiticus cytosine deaminase by immobilization on calcium alginate beads improved enzyme operational stability.
abstract: Cytosine deaminase (CD) from Aspergillus parasiticus, which has half-life of 1.10 h at 37°C, was stabilized by immobilization on calcium alginate beads. The immobilized CD had pH and temperature optimum of 5 and 50°C respectively. The immobilized enzyme also stoichiometrically deaminated Cytosine and 5-fluorocytosine (5-FC) with the apparent K(M) values of 0.60 mM and 0.65 mM respectively, displaying activation energy of 10.72 KJ/mol. The immobilization of native CD on calcium alginate beads gave the highest yield of apparent enzymatic activity of 51.60% of the original activity and the enzymatic activity was lost exponentially at 37°C over 12 h with a half-life of 5.80 h. Hence, the operational stability of native CD can be improved by immobilization on calcium alginate beads.
authors.affiliation: Department of Biochemistry, Faculty of Science, University of Maiduguri , Maiduguri , Nigeria.
authors.forename: H
authors.initials: H
authors.lastname: Zanna
authors.forename: A J
authors.initials: AJ
authors.lastname: Nok
authors.forename: S
authors.initials: S
authors.lastname: Ibrahim
authors.forename: H M
authors.initials: HM
authors.lastname: Inuwa
mesh_terms: D000464:Alginates / Q000737:chemistry*; D001230:Aspergillus / Q000201:enzymology*; D043525:Cytosine Deaminase / Q000737:chemistry / Q000378:metabolism*; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008863:Microspheres
chemical_list: D000464:Alginates; D004800:Enzymes, Immobilized; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D043525:Cytosine Deaminase