Premium
Evidence for the Formation of a Radical‐Mediated Flavin‐N5 Covalent Intermediate
Author(s) -
Dai Yumin,
Valentino Hannah,
Sobrado Pablo
Publication year - 2018
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201800123
Subject(s) - flavin group , chemistry , iminium , catalytic cycle , semiquinone , photochemistry , redox , covalent bond , scavenger , radical ion , catalysis , reaction intermediate , radical , ion , enzyme , organic chemistry
The redox‐neutral reaction catalyzed by 2‐haloacrylate hydratase (2‐HAH) leads to the conversion of 2‐chloroacrylate to pyruvate. Previous mechanistic studies demonstrated the formation of a flavin‐iminium ion as an important intermediate in the 2‐HAH catalytic cycle. Time‐resolved flavin absorbance studies were performed in this study, and the data showed that the enzyme is capable of stabilizing both anionic and neutral flavin semiquinone species. The presence of a radical scavenger decreases the activity in a concentration‐dependent manner. These data are consistent with the flavin iminium intermediate occurring by radical recombination.