Kinetic Parameters of Urease Immobilized on Modified Acrylonitrile Copolymer Membranes in the Presence and Absence of Cu(II) Ions

Abstract

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). [Diagram: see text]

Catalytic performances of chemically immobilized urease under static and dynamic conditions: A comparative study

“…The result indicates that the maximum reaction rate of urease immobilized membrane under dynamic conditions is enhanced which might be due to acceleration of mass transfer with continuous permeation of substrate through the membrane. Similar results have also been reported in the literature [43,44].…”

The influence of the support nature on the kinetics parameters, inhibition constants and reactivation of immobilized acetylcholinesterase

“…The color of the hydrolyzed yellowish/red PAN membrane was turned into white. After that, the membrane was immersed in 100 cm 3 of 10% (v/v) ethylenediamine aqueous solution for 60 min at room temperature [33]. After this step the obtained M-PAN membrane were washed in bi-distilled water to remove the EDA excess.…”

Application of immobilized horseradish peroxidase onto modified acrylonitrile copolymer membrane in removing of phenol from water

“…The modification of the acrylonitrile copolymer membranes was carried out by sequential processing of the membrane with NaOH and ethylenediamine (EDA), respectively, which had been described in a previous article of ours [15].…”