Glycoside Metabolizing Oxidoreductase D3dgpA from Human gut bacterium Provisionally Accepted

Heji Kim¹ Huynh Thi Ngoc Mi¹ Joong-Hoon Ahn² Jong Suk Lee³ Bekir Engin Eser⁴ Jongkeun Choi⁵ Jaehong Han^1*

• ¹Chung-Ang University, Republic of Korea
• ²Konkuk University, Republic of Korea
• ³Gyeonggido Business & Science Accelerator, Republic of Korea
• ⁴Aarhus University, Denmark
• ⁵Chungwoon University, Republic of Korea

The Gfo/Idh/MocA family enzyme DgpA was known to catalyze the regiospecific oxidation of puerarin to 3"-oxo-puerarin in the presence of 3-oxo-glucose. Here we discovered that D3dgpA, dgpA cloned from human gut bacterium Dorea sp. MRG-IFC3, was able to catalyze the regiospecific oxidation of various C-/O-glycosides, including puerarin, in the presence of methyl β-D-3-oxo-glucopyranoside. While C-glycosides were converted to 3"-and 2"-oxo-products by D3dgpA, O-glycosides resulted in the formation of the aglycones and hexose enediolone from the 3"-oxo-products. From the DFT calculations, it was found that isomerization of 3"-oxo-puerarin to 2"-oxo-puerarin required small activation energy of 9.86 kcal/mol, and the O-glycosidic bond cleavage of 3"-oxo-products was also thermodynamically favored with a small activation energy of 3.49 kcal/mol. In addition, the reaction mechanism of D3dgpA was discussed in comparison to those of Gfo/Idh/MocA and GMC family enzymes. Robust reactivity of D3dgpA was proposed as a new general route for the derivatization of glycosides.