Enzyme-polymer conjugates are complex molecules with great practical significance. This work was designed to develop a novel enzyme-polymer conjugate by covalently coupling a zwitterionic polymer with side dimethyl chains (pID) to

Candida rugosa

lipase (CRL)

via

the reaction between the anhydrides of polymer chains with the amino groups of the enzyme. The resulting two CRL-pID conjugates with different pID grafting densities were investigated in term of the catalytic activity

stability and structural changes. In comparison with native CRL

both the CRL conjugates displayed 2.2 times higher activity than the native enzyme

and showed an increase in the maximum reaction rate (

V

max

) and a decrease in the Michaelis constant (

K

m

)

thus resulting in about three-fold increases in the catalytic efficiency (

k

cat

/

K

m

). These are mainly attributed to the activation of lipase by the hydrophobic alky side chains. Moreover

the thermostability and pH tolerance of the lipase conjugates were significantly enhanced due to the stabilizing effect of the zwitterion moieties. For instance

a five-fold increase of the enzyme half

-life at 50℃ for the high-pID conjugated CRL was observed. Spectroscopic studies reveal that the pID conjugation protected the enzyme in the changes in its microenvironment and conformation

well correlating with enhanced activity and stability of lipase conjugates. The findings indicate that enzyme conjugation to the zwitterionic polymer is promising for improving enzyme performance and deserves further development.