In this work

four polymer-grafted Candida rugosa lipase (CRL) were synthesized via atom transfer radical polymerization by grafting hydroxyethyl methacrylate (HEMA)

glycidyl methacrylate (GMA)

propyl methacrylate (nPMA) and butyl methacrylate (BMA) onto CRL surface using N-(bromoisobutyryloxy) succinimide as the initiator. The results of CD and fluorescence emission spectra showed that the helical and sheet contents of CRL increased with polymer grafting

and exhibited a positive relation with the length of alkyl group in the monomer. Furthermore

a blue shift was also observed in fluorescence emission spectra of polymer-grafted CRL

meaning that polymer-grafted CRL had a more compact structure than wide-type CRL. Activity measurement of polymer-grafted CRL further showed that polymer grafting led to a significant increase of enzymatic activity of CRL in the order of CRL

HEMA-g-CRL = GMA-g-CRL

nPMA-g-CRL and BMA-g-CRL. With an increase of the length of alkyl group in the monomer

moreover

Michaelis parameter of CRL decreased from 0.17 mmol·L-1 to 0.09 mmol·L-1 whereas turnover number increased from 67 to 182 s-1. Therefore

catalytic efficiency of polymer-grafted CRL enhanced greatly and the catalytic efficiency BMA-g-CRL was 3.28 times as high as that of wide-type CRL. It indicated that polymer grafting improved the movement of lid structure

leading to the exposure of the active site in CRL and enhancing the substrate transformation. Stability tests show that polymer grafting enhances the thermal stability of the CRL and broadens its pH range. The research proposed a novel methodology to regulate the CRL activity by polymer grafting

and exhibited the influence of alkyl groups of the monomers to CRL activity. The result in this research provided a benefit guidance for rational screening of monomer molecules to improve the performance of lipase in industrial biotransformation.