Highly multilayered urease decomposes highly concentrated urea.
Urease was immobilized at a density of 1.2 g of urease per gram of a matrix via ion-exchange binding of urease to an anion-exchange polymer chain grafted onto a pore surface of a porous hollow-fiber membrane and subsequent cross-linking of urease with transglutaminase. Urea was hydrolyzed during the permeation of a urea solution, the concentration of which ranged from 2 to 8 M, through the pores of the resultant membrane with a thickness of approximately 1 mm. Quantitative hydrolysis of 4 M urea was achieved at a permeation rate lower than 1 mL/h, i.e., a residence time longer than 5.1 min, at ambient temperature. This performance is ascribed to convective transport of urea through the pores rimmed by the urease-immobilized polymer chains at a high density. Urease was denatured in the presence of urea at concentrations higher than 6 M while hydrolyzing urea.
Kobayashi
Satoshi
S
Department of Materials Technology, Faculty of Engineering, Chiba University, 1-33 Inage, Chiba 263-8522, Japan.
Yonezu
Shinji
S
Kawakita
Hidetaka
H
Saito
Kyoichi
K
Sugita
Kazuyuki
K
Tamada
Masao
M
Sugo
Takanobu
T
Lee
William
W
D000327:Adsorption; D002852:Chromatography, Ion Exchange / Q000379:methods; D004800:Enzymes, Immobilized / Q000737:chemistry; D006868:Hydrolysis; D008567:Membranes, Artificial; D020959:Polyethylene; D012995:Solubility; D014462:Ultrafiltration / Q000295:instrumentation / Q000379:methods*; D014508:Urea / Q000737:chemistry*; D014510:Urease / Q000737:chemistry*
D004800:Enzymes, Immobilized; D008567:Membranes, Artificial; D014508:Urea; D020959:Polyethylene; D014510:Urease