Genes of interest were synthesized by GeneArt (ThermoFisher, Darmstadt, Germany). Enzymes were expressed in E. coli I q (NEB, Frankfurt am Main, Germany) using EnPresso ® B medium (Enpresso, Berlin, Germany) based on the manufacturer's recommendations. Briefly, a 50 mL main culture was inoculated either from a fresh transformation plate or an LB preculture. Protein expression was induced by the addition of 200 µM IPTG. Cells were harvested by centrifu-gation and stored at -20 °C until further use. For purification, the cell pellet was resuspended in binding buffer (50 mM NaH 2 PO 4 , 300 mM NaCl, 10 mM imidazole, pH 8) including 0.1 mM phenylmethylsulfonyl fluorid (PMSF), 1 mg mL -1 lysozyme, 1 mM MgCl 2 and 0.6 mg mL -1 DNase. After incubation for 30 min at room temperature, cells were disrupted by sonification and prepurified by heat treatment for 20 min at 80 °C. After centrifugation the clear supernatant was loaded onto 0.5 to 2 mL Ni-NTA agarose (Jena Bioscience, Jena, Germany) columns. The columns were washed 4 times with 2 column volumes (CV) of washing buffer (binding buffer with 20 mM imidazole) and 6 times with 0.5 CV of elution buffer (binding buffer with 250 mM imidazole). The buffer of the elution fractions was exchanged by dialysis to 50 mM Tris-HCl pH 7.6 and enzymes were stored in 50% (v/v) glycerol at -20 °C.