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Kinetic Parameters of Urease Immobilized on Modified Acrylonitrile Copolymer Membranes in the Presence and Absence of Cu(II) Ions
Author(s) -
Godjevargova Tzonka,
Gabrovska Katya
Publication year - 2005
Publication title -
macromolecular bioscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.924
H-Index - 105
eISSN - 1616-5195
pISSN - 1616-5187
DOI - 10.1002/mabi.200400188
Subject(s) - chemistry , acrylonitrile , membrane , urease , metal ions in aqueous solution , nuclear chemistry , immobilized enzyme , metal , kinetics , inorganic chemistry , polymer chemistry , copolymer , enzyme , organic chemistry , polymer , biochemistry , physics , quantum mechanics
Summary: Poly(acrylonitrile‐methylmethacrylate‐sodium vinylsulfonate) membranes were subjected to seven different chemical modifications and the amount of the newly formed groups was measured for each membrane. Urease was then covalently immobilized onto the modified membranes and the amount of bound protein was determined. The kinetic parameters V max and K m of the immobilized urease were studied under static and dynamic conditions. Results showed that the rate of the enzyme reaction was higher for the membranes modified with NH 2 OH · H 2 SO 4 , NH 2 NH 2  · H 2 SO 4 , NaOH + EDA and NaOH + GA + EDA. It was confirmed that the reaction rate, measured under dynamic conditions, was higher than that one determined under static conditions. The influence of Cu(II) ions, as inhibitors, on the enzyme reaction kinetics ( V i and K i ) was also investigated. It turned out that the most sensitive membranes towards Cu(II) were those modified with NH 2 NH 2  · H 2 SO 4 , NaOH + EDA and H 2 O 2 . The results initiated further investigations on the influence of other heavy metal ions (Cd(II), Zn(II), Ni(II) and Pb(II)) over urease bound to a NH 2 OH · H 2 SO 4 ‐modified membrane. It was found that the inhibition effect of the heavy metal ions over immobilized urease decreases in the order: Cu(II) > Cd(II) > Zn(II) > Ni(II) > Pb(II).

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