Immobilization of Endonuclease A from Serratia marcescens on cellulose membranes

The removal of ds-DNA constitutes an indispensable step in numerous biotechnological production processes. In many cases, endonucleases are employed for this purpose. The objective of this study was to investigate the immobilization of Endonuclease A from Serratia marcescens onto cellulose filters, which could later be used in biotechnological production processes. The filters were treated with p-toluenesulfonyl chloride prior to enzyme functionalization, and tosyl loading was confirmed by HPLC. Enzyme activity after immobilization was investigated using a colorimetric assay. The functionalization of the filters was most effective when they were treated with 0.5 M NaOH prior to reaction with p-toluenesulfonyl chloride. The subsequent endonuclease immobilization process was screened under various pH conditions and was most successful when conducted at a slightly acidic pH. However, it was also observed that functionalization with p-toluenesulfonyl chloride was not necessary to immobilize the endonuclease onto the cellulose membranes, as initially assumed. This indicates that immobilization can proceed through a pathway independent of the presence of tosylate groups on the surface of the cellulose filters.