Immobilization of urease from pigeonpea (Cajanus cajan L.) on flannel cloth using polyethyleneimine

Urease of pigeonpea has been immobilized on polyethyleneimine-activated cotton cloth followed by cross-linking with dimethyl suberimidate. Optimum immobilization (56%) was obtained at a protein loading of 1.2 mg/5 x 5 cm(2) cloth piece. The immobilized enzyme stored in 0.1 IM Tris/acetate buffer, pH 6.5, at 4 degrees C had a t(1/2) of 70 days. There was practically no leaching of the enzyme from the immobilization matrix in 15 days. The immobilized enzyme was used 7 times at an interval of 24 h between each use with 75% residual activity at the end of the period. Blood urea analysis was carried out with immobilized urease for some clinical samples.