Abstract
CMP-sialic acid synthetase ( CSS ) was immobilized on magnetic nanoparticles ( MNPs ) by combining the intein expression system and native chemical ligation. Without tedious enzyme purification steps, the enzyme was site specifically and covalently immobilized via its C terminus to MNP and could be directly separated from aqueous solution by a magnet. The MNP-CSS was stable for long-term storage ( 30 days at 4 oC ) and could be reused without loss of activity. Compared with conventional immobilization by random amide bond formation, our method of site-specific immobilization of CSS yielded much higher activity. These features of MNP-CSS suggest that it, and similarly immobilized enzymes, may be amenable to practical applications in organic synthesis.