Poly immobilized lipase activity

Enzyme activity for the polymerization of lactones was improved by the immobilization on Celite [93]. Immobilized lipase PF adsorbed on a Celite showed much higher catalytic activity than that before the immobilization. The catalytic activity was further enhanced by the addition of a sugar or poly(ethylene glycol) in the immobilization. Surfactant-coated lipase efficiently polymerized the ring-opening polymerization of lactones in organic solvents [94]. 

Apart from CALB other enzymes were shown to be able to successfully polymerize lactones. For instance Lipase PS-30, immobilized on Celite, was used as catalyst to study PDL-ROP under bulk reaction conditions. Poly(PDL) with M = 62000 and PDI 1.9 was reported [76]. Gross and coworkers could show that Humicola insolens cutinase (HiC) showed a high catalytic activity for enzymatic ROP of e-CL and PDL [87]. Poly(e-CL) with M n = 16000 (M /lVf = 3.1), in >99% yields was produced in bulk (70 °C, 24h) with 0.1% w/w immobilized HiC. Furthermore, using immobilized HiC in toluene (70 °C, 24h), PDL was converted to poly(PDL) (99% yield) with M = 44600 and Mw/M = 1.7. 

Functions.—Heparin fractionated by gel filtration appeared to bind to two sites on antithrombin III (association constants 0.6 x 10 and 0.2 x 10 moll" ), whereas heparin prepared by affinity chromatography on matrix-bound antithrombin III appeared to bind to only one site (association constant 2.3 x 10 moll ). These results suggest that one of the binding sites on antithrombin III does not bind the most active heparin components, but accommodates heparin-like molecules which, although similar in size to the active heparin components, have little or no anticoagulant activity. Heparins with high or low affinities for antithrombin III exhibited no differences in their abilities to bind lipoprotein lipase. Studies of the interaction between the lipoprotein lipase from cow s milk and Sepharose-immobilized heparin have shown that heparin is poly-disperse. Whereas heparin facilitated complex formation between a-thrombin and antithrombin III, it had little effect on the interaction between p-thrombin and antithrombin III. ... 

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