Chalcone Isomerase from Eubacterium ramulus Catalyzes the Ring Contraction of Flavanonols.

ABSTRACT: The enzyme catalyzing the ring-contracting conversion of the flavanonol taxifolin to the auronol alphitonin in the course of flavonoid degradation by the human intestinal anaerobe Eubacterium ramulus was purified and characterized. It stereospecifically catalyzed the isomerization of (+)-taxifolin but not that of (-)-taxifolin. The K_m for (+)-taxifolin was 6.4 ± 0.8 μM, and the V_max was 108 ± 4 μmol min^-1 (mg protein)^-1 The enzyme also isomerized (+)-dihydrokaempferol, another flavanonol, to maesopsin. Inspection of the encoding gene revealed its complete identity to that of the gene encoding chalcone isomerase (CHI) from E. ramulus Based on the reported X-ray crystal structure of CHI (M. Gall et al., Angew Chem Int Ed 53:1439-1442, 2014, http://

SUBMITTER: Braune A 

PROVIDER: S-EPMC5055601 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature