Biochemical and Biophysical Research Communications, Vol.521, No.4, 997-1002, 2020
Mechanism of the salt activation of laccase Lac15
Laccases (benzenediol: oxygen oxidoreductases, EC184.108.40.206) can oxidize various substrates, and those which are tolerant to and even activated by salts have attracted a lot of attention due to their application potential in certain industries. The mechanism of the salt activation of laccases is awaiting to be elucidated yet. Our previous study (Li, Xie et al. 2018) supposed that the salt activation of marine laccase Lac15 might be attributed to ion specifically binding to some local sites to interfere substrate binding and/or electron transfer. In this study, we found two sites whose mutations resulted in elimination of the salt activation of Lac15's activity towards catechol and dopamine respectively, and revealed that the mutations affected the activity by altering both E-m and k(cat), demonstrating the supposed mechanism. A model for the salt activation of laccases was accordingly proposed, albeit some details are to be elucidated. (C) 2019 Elsevier Inc. All rights reserved.