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α-l-Rhamnosidase of Aspergillus terreus immobilized on ferromagnetic supports

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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).

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Acknowledgments

The authors thank CNPq that financed this work and awarded a post-doc scholarship to F. Soria and a fellowship to L.B. Carvalho Jr. They are also grateful to Mr. Otaviano Tavares da Costa for his technical collaboration.

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Correspondence to Luiz Bezerra Carvalho Jr.

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Soria, F., Ellenrieder, G., Oliveira, G.B. et al. α-l-Rhamnosidase of Aspergillus terreus immobilized on ferromagnetic supports. Appl Microbiol Biotechnol 93, 1127–1134 (2012). https://doi.org/10.1007/s00253-011-3469-y

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  • DOI: https://doi.org/10.1007/s00253-011-3469-y

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