Adsorption immobilization of Candida rugosa lipases on polypropylene hollow fiber microfiltration membranes modified by hydrophobic polypeptides

Poly(γ-ethyl-l-glutamate) (PELG) and poly(γ-stearyl-l-glutamate) (PSLG), two polypeptides with short and long hydrophobic side chains, respectively, were tethered on the polypropylene hollow fiber microfiltration membrane (PPHFMM) surface through the ring opening polymerization of N-carboxyanhydride of γ-ethyl-l-glutamate (γ-stearyl-l-glutamate) initiated by amino groups. Lipases from Candida rugosa were immobilized on these membranes by adsorption. Results on the basis of the enzyme adsorption capacity, activity and thermal stability were compared with those of the nascent PPHFMM. It was found that, as for the modified PPHFMM, the adsorption capacities of lipase are lower than that of the nascent ones, but the activity retention of the immobilized enzymes increases from 57% to 72% and to 62%, respectively for the PSLG-modified and PELG-modified PPHFMM. In addition, the experimental results of thermal stability show that the residual activity of the immobilized lipases at 50 °C for 2 h is respectively 64% for the PELG-modified PPHFMM and 58% for the PSLG-modified PPHFMM, which are higher than that of the nascent ones.