Abstract:

A novel enzyme immobilization method was developed. The enzyme was immobilized using single-stranded DNA modified magnetic nanoparticles as carriers through DNA strand displacement reactions. Alkaline phosphatase (ALP) was immobilized with partly complementary capture DNA-functionalized nanoparticles (MNPs@capDNA) by highly specific Watson-Crick hybridization to obtain the MNPs@DNA-ALP. For trypsin immobilization, the MNPs@DNA-Trypsin was obtained by the incubation of MNPs@DNA-ALP with trypsin-target DNA conjugates to trigger a toehold-mediated DNA strand displacement reactions. The enzymes can be replaced without damage by the immobilized enzyme procedure. Therefore, the strategy gave the possibility to recycle the enzymes and save the production cost. The immobilized trypsin exhibited excellent reusability and improved digestion performance. The enzymatic activity remained more than 86% after 10 cycles. And the sequence coverage of myoglobin (Myo) was 95%±0% (n=3), which was higher than that obtained by the free enzyme for 12 h. The strategy provides a promising alternative platform for the enzyme immobilization and can be used in a large variety of enzymatic reactions.

Key words: DNA strand displacement reactions, enzyme digested, high performance liquid chromatography (HPLC), immobilization enzyme, mass spectrometry (MS)