Identification\nof Enzymes and Their Key Action Sites\nfor Histamine Degradation in Mulberry Fruit Wine by Lactiplantibacillus plantarum

In this study, the glyceraldehyde-3-phosphate dehydrogenase\n(GAPDH)\nand multicopper oxidase (MCO) of Lactiplantibacillus\nplantarum W155 with histamine degradation ability\nwere expressed. The mulberry fruit wine (MFW) histamine degradation\nabilities of GAPDH and MCO were 20.81% and 37.67%, respectively. Compared\nwith the control group, the MFW treated by GAPDH showed higher total\nphenolic (1.17 g GAE/L) and total flavonoid (0.31 g RE/L) contents,\nwhile MFW treated by MCO presented similar total phenolic (1.00 g\nGAE/L) and total flavonoid (0.29 g RE/L) concentrations. Furthermore,\nthe optimal pH and temperature of GAPDH were 6.0 and 40 °C, respectively,\nwhile the optimal pH and temperature of MCO were 3.0 and 50 °C,\nrespectively. Meanwhile, the key action sites for histamine degradation\nof GAPDH and MCO were minded via homology modeling, molecular docking,\nand site-directed mutagenesis. Val209 and Ile290 were confirmed as\nthe key action sites for GAPDH, while Qln402 and Leu420 were the pivotal\naction sites for MCO. Above findings indicated that both GAPDH and\nMCO of L. plantarum W155 could be used\nto control the histamine of MFW, and the key action sites of these\ntwo enzymes could be used as targets for their subsequent modification.