??????????????? ?????? LiPH8??? helix-loop ??????????????? ????????? ?????? ?????? pH ??? ??????????????? ????????? ????????? ?????? ?????? ??????

Department of Chemical EngineeringThe development of acid-resistant lignin peroxidase is needed to improve lignin degradation efficiency using enzymes. Therefore, we aimed to improve acidostability by strengthening the loop-helix interactions to enhance the overall structural stability under acidic condition. A new interaction was introduced by adding one disulfide bridge and one ionic bridge to LiPH8 derived from Phanerochaete chrysosporium. As a result, we found that the pH stability of the acidic stable mutant (triple mutant, S49C/A67C/H239E) was 22.9 times higher than that of the wild type. X-ray crystallography analysis suggested the convincing proof of newly formed one disulfide bridge between S49C and A67C and one ionic salt bridge between H239E and R234 (PDB id:6ISS). In addition, the melting temperature of the mutant was 2.8 ??? higher than that of the wild type in the acidic condition, which strongly indicates that reinforcing the loop-helix interaction will be essential for increased stability under acid pH as well as thermal stability.clos