Studies on properties of immobilized urokinase.

Abstract

Human urokinase was immobilized on an ethylene vinyl acetate copolymer surface. Soluble urokinase showed its maximum activity at pH 8.5, while the immobilized enzyme was most active at pH 9.0. Apparently, the shift in optimal pH was due to the polyanionic nature of the carrier surface on which the enzyme was immobilized. Optimal temperatures of soluble urokinase and immobilized enzyme were identical, i.e., 37 degrees C. The stability of immobilized enzyme against thermal degradation was several times higher than that of the soluble enzyme. Its stability at higher temperatures is one of the main reasons for the clinical use of immobilized urokinase as an antithrombotic material.

Kinetic behaviour and stability of Escherichia coli ATCC27257 alkaline phosphatase immobilised in soil humates

“…23,51 Results obtained on the effect of pH on enzyme immobilisation are usually unpredictable: in some cases both the optimal pH and the pH/activity profile change upon immobilisation, whereas in other cases they do not. 55 The dependence of alkaline phosphatase activity on temperature is shown in Fig 4. The free enzyme showed its greatest activity at 60°C, while the immobilised enzyme retained 90% of activity between 80 and 100°C. The optimum temperature is determined by the balance between the effect of temperature on the rate of the enzyme reaction and its effect on the rate of destruction of the enzyme.…”

Covalently immobilized thrombomodulin inhibits coagulation and complement activation of artificial surfaces in vitro

“…To avoid these problems molecular products or components of endothelial cells like heparin [10][11][12][13][14][15][16][17], plasminogen-activators (tissue-and urokinase-type [18][19][20][21][22][23][24]) and NO [25] were applied instead.…”

Increased Sensitivity of Cholera Toxin Detection by Enzyme‐Linked Immunosorbent Assay with Chemical Immobilization of Antibody onto Nylon Surface Providing Hydrophobicity

“…N. KOIKE ET AL previously for immobilization of an enzyme (13), was used with some modifications. SMA was introduced onto the nylon surface as schematically shown in Fig.…”

“…The 15 min) with water-free acetone. After introducing SMA (or MAMEC) onto the nylon slip, MAb (protein concentration; 2 Kg/m1) suspended in phosphate-buffered saline (PBS) was reacted (immobilized) on the slip at 25 C overnight (4), resulting in immobilization of antibody on the nylon surface by peptide bonds formed between the antibody amino group and the nylon surface anhydride group (13). The nylon slip was treated with 2%(w/v) bovine-serum albumin to block further reaction with non-specific proteins.…”

“…To estimate the quantity of protein immobilized by these treatments on the nylon surface, urokinase (purchased from Nihon Seiyaku Co.), which has no hydrophobic or hydrophilic cluster (6), was immobilized and the activity of the enzyme was measured. Urokinase known as an enzyme with fibrinolytic activity, was immobilized on the MAMEC-or SMA-treated nylon surface and the amount of protein immobilized on the surface was estimated from the activity of the immobilized urokinase (13). Although the same amount of urokinase was used for chemical immobilization (127 IU in 1 ml), the activities of urokinase on MAMEC-treated and SMA-treated surfaces were 30 and 1 IU/cm', respectively, whereas that of polystyrene or untreated nylon was 0.3 IU/cm'.…”