Here, we present the full-length protocol for purifying the recombinant MOS1 transposase from insect cells used in our recent publication (Pflieger et al., 2014), which involved a N-terminal MBP-tag and maltose-affinity chromatography.

Due to their overall basic properties, transposases are often difficult to purify, especially because they tend to aggregate. Since the 90s, we chose a method of purification without a denaturation step. Our first priority was to preserve the 3D structure of the protein in order to maintain its biochemical activities with the highest specific activity. Nevertheless, our production/purification made from bacteria regularly contain truncated products (or degradation products) and their levels increase with concentration of purified transposase. In contrast, production/purification made from eukaryotic cells do not contain such degradation product. We thus developed a protocol involving the pVL1392 baculovirus transfer vector and the BaculoGold^TM baculovirus expression system, allowing the expression of recombinant MOS1 from baculovirus-infected Sf21 cells.