Degradation of halogenated aromatic compounds

Abstract

Due to their persistence, haloaromatics are compounds of environmental concern. Aerobically, bacteria degrade these compounds by mono- or dioxygenation of the aromatic ring. The common intermediate of these reactions is (halo)catechol. Halocatechol is cleaved either intradiol (ortho-cleavage) or extradiol (meta-cleavage). In contrast to ortho-cleavage, meta-cleavage of halocatechols yields toxic metabolites. Dehalogenation may occur fortuitously during oxygenation. Specific dehalogenation of aromatic compounds is performed by hydroxylases, in which the halo-substituent is replaced by a hydroxyl group. During reductive dehalogenation, haloaromatic compounds may act as electron-acceptors. Herewith, the halosubstituent is replaced by a hydrogen atom.

Degradation of 2,7-dichlorodibenzo-p-dioxin by the lignin-degrading basidiomycete Phanerochaete chrysosporium

“…3). Enzyme-catalyzed C-0-C bond cleavage of PCDDs has not been observed previously (5,9,21). This reaction is catalyzed by LiP alone, albeit at a slow rate.…”

“…Since PCDDs are relatively chemically stable and lipophilic in nature (25,40,43), their accumulation in the food chain has been predicted and observed (3,14,29,36). In addition, studies have concluded that these compounds are degraded very slowly by soil bacteria (9,38,41), probably increasing their environmental impact.…”

“…While very slow degradation of TCDD has been reported for a number of bacteria and traces of polar metabolites are generated, for the most part these pathways have not been elucidated (9). The slow cometabolism of mono-, di-, and trichlorodioxins by a biphenyl-utilizing Beijerinkia strain has been reported (34).…”

PSMA Ligands for PET Imaging of Prostate Cancer

“…In contrast, small-molecule PSMA ligands bind to the active site in the extracellular domain of PSMA and are internalized and endosomally recycled, leading to enhanced tumor uptake and retention and high image quality (24)(25)(26)(27). The most widely used 68 Ga-labeled PSMA ligands for PET imaging are 68 Ga-PSMA-11 ( 68 Ga-PSMA-HBED-CC) and the theranostic agents 68 Ga-PSMA-617 and 68 Ga-PSMA-I&T (28,29).…”

The Three-dimensional Structure of 4-Hydroxybenzoyl-CoA Thioesterase from Pseudomonas sp. Strain CBS-3

“…These bacterial species have attracted significant research attention for their possible employment as bioremediation agents (2)(3)(4)(5). Of particular interest is the soil-dwelling microbe, Pseudomonas sp.…”