title: α-L-rhamnosidase of Aspergillus terreus immobilized on ferromagnetic supports.
abstract: α-L-rhamnosidase from Aspergillus terreus was covalently immobilized on the following ferromagnetic supports: polyethylene terephthalate (Dacron-hydrazide), polysiloxane/polyvinyl alcohol (POS/PVA), and chitosan. The powdered supports were magnetized by thermal coprecipitation method using ferric and ferrous chlorides, and the immobilization was carried out via glutaraldehyde. The activity of the Dacron-hydrazide (0.53 nkat/μg of protein) and POS/PVA (0.59 nkat/μg of protein) immobilized enzyme was significantly higher than that found for the chitosan derivative (0.06 nkat/μg of protein). The activity-pH and activity-temperature profiles for all immobilized enzymes did not show difference compared to the free enzyme, except the chitosan derivative that presented higher maximum temperature at 65 °C. The Dacron-hydrazide derivative thermal stability showed a similar behavior of the free enzyme in the temperature range of 40-70 °C. The POS/PVA and chitosan derivatives were stable up to 60 °C, but were completely inactivated at 70 °C. The activity of the preparations did not appreciably decrease after ten successive reuses. Apparent K (m) of α-L-rhamnosidase immobilized on magnetized Dacron-hydrazide (1.05 ± 0.22 mM), POS/PVA (0.57 ± 0.09 mM), and chitosan (1.78 ± 0.24 mM) were higher than that estimated for the soluble enzyme (0.30 ± 0.03 mM). The Dacron-hydrazide enzyme derivative showed better performance than the free enzyme to hydrolyze 0.3% narigin (91% and 73% after 1 h, respectively) and synthesize rhamnosides (0.116 and 0.014 mg narirutin after 1 h, respectively).
authors.affiliation: Instituto de Investigaciones para la Industria Química (INIQUI), Universidad Nacional de Salta-CONICET, Buenos Aires, 177-4400 Salta, Argentina.
authors.forename: Fernando
authors.initials: F
authors.lastname: Soria
authors.forename: Guillermo
authors.initials: G
authors.lastname: Ellenrieder
authors.forename: Givanildo Bezerra
authors.initials: GB
authors.lastname: Oliveira
authors.forename: Mariana
authors.initials: M
authors.lastname: Cabrera
authors.forename: Luiz Bezerra
authors.initials: LB
authors.lastname: Carvalho
mesh_terms: D001230:Aspergillus / Q000201:enzymology*; D001709:Biotechnology / Q000379:methods*; D048271:Chitosan / Q000737:chemistry; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000378:metabolism*; D044950:Flavanones / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D059346:Magnets; D011093:Polyethylene Terephthalates / Q000737:chemistry; D011142:Polyvinyl Alcohol / Q000737:chemistry; D012210:Rhamnose / Q000378:metabolism; D012833:Siloxanes / Q000737:chemistry; D013696:Temperature
chemical_list: D004800:Enzymes, Immobilized; D044950:Flavanones; D011093:Polyethylene Terephthalates; D012833:Siloxanes; D011142:Polyvinyl Alcohol; D048271:Chitosan; D006026:Glycoside Hydrolases; C022525:alpha-L-rhamnosidase; C005274:naringin; D012210:Rhamnose