Freeze-drying of lignin peroxidase: influence on enzyme activity and stability

The effect of different lyoprotectants (sucrose, dimethyl-succinate buffer (DMS), bovine serum albumin (BSA), mannitol and dextran, mw 60kDa) on the stability of the enzyme lignin peroxidase (LiP, EC number: 1.11.1.-), both during the freeze-drying process and storage were investigated. The shelf stability tests were performed at 4°C and 27°C. Both DMS buffer and sucrose showed a good protective action: the former was particularly effective during the process, while the latter improved the stability during storage. In contrast, mannitol and dextran had negative effects, reducing the activity also in the lignin peroxidase solution. BSA was discarded because, in the range of compatible concentrations with LiP, it does not confer a consistent structure to the freeze-dried product.