HheG and its variants were produced in 500 ml Terrifc Broth (TB) (per liter: 4 ml glycerol, 12 g peptone, 24 g yeast extract, 0.17 M KH2PO4, 0.74 M K2HPO4) supplemented with 50 µg/ml kanamycine. Further, 50 ml of an overnight culture in induction, and 0.2 mM Isopropyl-β-D-thiogalactopyranosid (IPTG) was inoculated with 10% (v/v) preculture. In detail, protein expression was initiated by adding 50 ml of an overnight preculture (grown at 37 °C in LB medium) and 0.2 mM IPTG. Then, cultivation in shake flasks was performed for 24 h at 22 °C and 220 rpm before cell pellets were collected by centrifugation (20 min, 3494 g, 4 °C) and stored at -20 °C until further purification.