The Influence of the Micro-Surrounding on ET Pathways between Heme2 and W199 in MauG

• 1、School of Chemistry and Chemical Engineering of Chongqing University,Chongqing 401331

Abstract：The diheme enzyme MauG catalyzes the posttranslational modificationof the precursor protein of methylamine dehydrogenase(preMADH) to complete biosynthesis of its protein-derived tryptophan tryptophylquinone (TTQ) cofactor. The catalytic process requires the production of a special heme structure（diHeme-Fe(IV)/Fe(IV)=O，bis-Fe(IV)）, and this high valence state bis-Fe (IV) is not directly connected to preMADH, from the substrate βTrp108 to bis-Fe (IV) that requires six-electrons to be transferred over long-range . Wherein, W199 is located in the middleThe InThe Influence of the Micro-Surrounding on Electron Transfer Pathways between Heme2 and W199 in MauGfluence of the Micro-Surrounding on Electron Transfer Pathways between Heme2 and W199 in MauG position of MauG-preMADH, plays an important role in electron transfer. And the six-coordinated low spin Heme2 that is closer to the substrate. We were using the DFT method to investigated the electron transfer from Heme2 to Trp199 in several cases with Heme2-Fe (IV / Ⅲ), Heme2 edge presence or absence of the carboxyl group, in the presence or absence of Ca2 + protein structures. The results show that Heme2_Fe (IV) can directly oxidize W199, Heme2_Fe (III) requires W199 to lose the side chain protons and then oxidize it, indicating that W199 is an important electron transfer intermediate. Through the analysis of the presence of carboxyl groups, we also confirmed that the carboxyl groups attached to the porphyrin ring also participate in electron hole transport, While Ca2 + is not only able to stabilize the structure, but also has a certain role in the regulation of electron transfer.

Keywords： MauG Heme2 Trp199 electron transfer