Dead-end metabolite

Nortemann B, A Glasser, R Machinek, G Remberg, H-J Knackmuss (1993) 5-hydroxyquinoline-2-carboxylic acid, a dead-end metabolite from the bacterial oxidation of 5-aminonaphthalene-2-sulfonic acid. Appl Environ Microbiol 59 1898-1903. 

Andersson BE, T Henrysson (1996) Accumulation and degradation of dead-end metabolites during treratment of soil contaminated with polycyclic aromatic hydrocarbons with five strains of white-rot fungi. Appl Microbiol Biotechnol 46 647-652. 

Exceptions exist to this tendency for ready incorporation of the initial transformation products of xenobiotic compounds into a common pathway. First, occasionally a product is formed which is unreactive in subsequent steps in a particular microorganism. Such partially degraded compounds have been referred to as dead-end metabolites (Knackmuss, 1981). An example of this is the 5-chloro-2-hydroxy-muconic acid semialdehyde produced by the meta cleavage of 4-chlorocatechol by a particular pseudomonad species ... 

Incomplete aerobic transformations may involve cometabolic transformations and reactions resulting in recalcitrant dead-end metabolites. Cometabolic o-hydroxylation of MCPs and DCPs by a phenol monooxygenase has been shown, for example, in a Pseudomonas sp. (Knackmuss Hellwig, 1978) and by the toluene dioxygenase reaction in Pseudomonas putida (Spain Gibson, 1988 Spain et al., 1989)- Cometabolic transformation of CPs is also possible in aerobic mixed culture systems. Phenol- and toluene-enriched cultures completely removed 2,4-DCP, and the toluene enrichment also removed 2,4,6-TCP and PCP (Ryding et al., 1994). This PCP attack by the toluene enrichment involved an o-hydroxylation. 

The most recent alteration ofBl 3 involved the introduction of another foreign gene to allow complete metabolism of para-cteso through transformation of the dead-end metabolite, 4-methyl-2-ene lactone, accumulated by the benzoate... 

HL 24-2, originally isolated for its ability to degrade 2,4-dinitrophenol [14], cotild also utilize picric acid as nitrogen source. The mutant HL-PM-1 transiently accumulated an orange-red metabolite, which was identified as a hydride-Meisenheimer complex of picric acid. This complex was further converted with release of nitrite. 2,4,6- Trinitrocyclohexanone was the dead-end metabolite of the degradation of picric acid. 

Increased production of the dead-end metabolite nitrobenzyl alcohol... 

Previously, reduction of aromatic nitro groups has been thought to increase the resistance of the molecule to biodegradation. Recent work (3, 34) has shown that reduction of the nitro group to the amine level can result in productive metabolism under anaerobic conditions. Complete reduction of nitro groups has been widely reported to occur in aerobic bacteria (20, 40). However, the amines produced by such reactions seem to be dead end metabolites under aerobic conditions. 

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